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US400S&P MidCap 400 IndexS&P MidCap 400 Index
US400What Is the S&P MidCap 400 Index (US400)?
TL;DR
The S&P MidCap 400 (US400) is a market-cap-weighted benchmark of 400 mid-sized U.S. companies that historically delivers superior long-run risk-adjusted returns versus both large-cap and small-cap peers, driven by the 'sweet spot' of growth potential combined with institutional stability.
The S&P MidCap 400 Index is the definitive benchmark for mid-size U.S. equities, comprising exactly 400 companies selected and maintained by S&P Dow Jones Indices to represent the middle tier of the American equity market by market capitalization. According to S&P Dow Jones Indices, the S&P 500, S&P MidCap 400, and S&P SmallCap 600 are "widely recognized as leading measures of U.S. equity market performance," with the MidCap 400 specifically bridging the large-cap S&P 500 and the small-cap S&P 600 within the broader S&P Composite 1500 family.
Index Construction and Weighting Methodology
The S&P MidCap 400 uses a float-adjusted market capitalization weighting methodology. Rather than weighting each constituent by its total shares outstanding, the index reflects only publicly tradable, or "free float," shares. This approach deliberately excludes shares held by insiders, controlling shareholders, or governments — ensuring the index represents genuinely investable market exposure accessible to institutional and retail participants alike. The result is a benchmark that more accurately mirrors real-world portfolio construction than a pure market-cap-weighted approach would allow.
Eligibility for inclusion is multi-dimensional and rigorous. Candidates must be U.S.-domiciled companies meeting a minimum public float threshold of at least 50% of total shares outstanding, alongside a minimum annual dollar value traded of at least 1.0x the float-adjusted market cap — a liquidity screen designed to ensure constituents can be efficiently tracked by passive vehicles. Critically, the S&P Index Committee also applies a profitability screen: companies must demonstrate positive as-reported earnings over the most recent quarter and over the most recent four consecutive quarters combined. This earnings requirement distinguishes the S&P family from purely size-based mid-cap benchmarks and contributes to its widespread adoption as an institutional standard.
Ongoing Reconstitution, Not Fixed Schedules
Unlike some benchmark families that rebalance on rigid quarterly calendars, the S&P MidCap 400 is reconstituted on an ongoing basis by the S&P Index Committee. Additions and deletions are event-driven, triggered by corporate actions such as mergers, acquisitions, bankruptcies, and IPOs reaching eligibility thresholds, as well as by companies graduating upward to the S&P 500 or migrating downward to the S&P 600. A recent illustration of this dynamic occurred on April 9, 2026, when DigitalOcean Holdings (NYSE: DOCN) was promoted from the S&P SmallCap 600 into the S&P MidCap 400, replacing Casey's General Stores (CASY), which itself graduated to the S&P 500 — a cascading series of reconstitutions triggered by broader M&A activity, according to data tracked in April 2026.
Role in Global Portfolios and Passive Capital
The S&P MidCap 400 underpins a substantial pool of passive capital and serves as the performance benchmark for active mid-cap equity managers worldwide. As of April 2026, tracking vehicles include the SPDR S&P 400 US Mid Cap ETF (SPX4) with approximately $4.1 billion in assets under management at an ongoing cost of 0.30%, according to Morningstar data, as well as the Vanguard S&P Mid-Cap 400 Growth Index Fund (VMFGX). Index inclusion carries material consequences for constituent companies: fund managers benchmarked to the S&P MidCap 400 must mechanically adjust holdings following any reconstitution, historically generating measurable shifts in trading volume and liquidity for newly added or removed companies.
For traders seeking leveraged exposure to U.S. mid-cap equity dynamics, CoinUnited.io offers US400 CFDs with up to 2000x leverage and zero trading fees — providing capital-efficient access to the same benchmark that institutional managers track globally.
Last updated: 2026-04-15
Key Insights
- Mid-cap indices occupy a structural 'sweet spot': constituent companies are large enough to have established business models and analyst coverage, yet small enough to deliver outsized earnings growth — a combination that has historically produced superior long-run risk-adjusted returns versus the S&P 500 and S&P 600 over full market cycles.
- Index reconstitution events are high-conviction short-term trading catalysts: additions to the S&P MidCap 400 trigger mechanical buying from hundreds of passive ETFs and mutual funds that must replicate the index, creating predictable demand spikes around effective dates that active traders can systematically exploit.
- The S&P MidCap 400 Growth sub-index outperformed the S&P 500 by more than 9 percentage points year-to-date through April 9, 2026, illustrating how mid-cap growth can decouple from large-cap indices during periods of investor rotation away from mega-cap concentration risk.
- Broad participation across both growth and value segments of the S&P MidCap 400 — with the Growth index at +9.08% YTD and the Value index at +5.44% YTD through April 9, 2026 — serves as a historically reliable bullish structural signal, contrasting with narrow-leadership markets that precede corrections.
- Macro valuation headwinds are real but asymmetric for mid-caps: while the Buffett Indicator at 216.96% and a forward P/E of 19.8x signal broad market overvaluation, mid-cap constituents tend to trade at a meaningful discount to S&P 500 mega-caps on a price-to-earnings basis, offering relative value within an expensive market.
Key Takeaways
Last updated: 2026-06-07- •US400 reflects broad market sentiment and is a benchmark for portfolio performance.
- •Key economic indicators — payrolls, CPI, PMI — drive index-level moves.
- •Index composition and sector weighting influence returns during rotation cycles.
Price & Market Structure
Trading Regime Status
Why Trade US400? Key Drivers, Catalysts & Risk Factors
The S&P MidCap 400 Index (US400) represents one of the most differentiated expressions of U.S. domestic economic conviction available to equity traders — offering a structural combination of earnings-quality screening, domestic revenue exposure, and high-velocity growth characteristics that neither large-cap nor small-cap benchmarks can fully replicate. As of April 2026, the index has delivered a year-to-date return of +7.31% through April 9, 2026, markedly outperforming the S&P 500's near-flat +0.01% over the same period, according to Franklin Templeton's "From the US Market Desk" report.
Domestic Revenue Sensitivity as a Structural Advantage
Unlike S&P 500 mega-caps, which derive a substantial share of revenues from international markets, S&P MidCap 400 constituents generate the majority of their revenues domestically. This structural characteristic makes US400 a higher-conviction expression of U.S. GDP growth, consumer spending trends, and business investment cycles than the headline large-cap index. When U.S. domestic economic momentum accelerates, mid-cap earnings respond more directly and with less dilution from foreign currency translation or geopolitical exposure. Franklin Templeton's Global Investment Management Survey, published in April 2026, forecasts real GDP growth of 2.5% for 2026 — a backdrop that, if realized, would disproportionately benefit domestically oriented mid-cap revenues relative to internationally diversified large-cap peers.
Earnings Quality Screen and the Growth Phase Advantage
The S&P MidCap 400's profitability eligibility requirement — mandating positive as-reported earnings over the most recent quarter and the trailing four quarters combined — structurally tilts the index away from speculative, pre-profit enterprises. This screen differentiates US400 from purely size-based mid-cap benchmarks and concentrates exposure in companies with demonstrated business models. Simultaneously, the mid-cap size range captures companies that are typically in their highest-velocity organic growth phase: established enough to have proven unit economics, yet not large enough to face the growth-rate compression that accompanies eventual S&P 500 inclusion. The S&P MidCap 400 Growth sub-index recorded a year-to-date return of +9.08% through April 9, 2026, according to Franklin Templeton, underscoring the contribution of this growth orientation to near-term performance.
Monetary Policy Amplification
Monetary policy transmission is materially amplified for mid-cap companies relative to their large-cap counterparts. Mid-sized companies typically carry higher proportional floating-rate debt loads and have more limited access to global capital markets for opportunistic refinancing. As a result, Federal Reserve rate decisions carry a measurably larger impact on mid-cap earnings trajectories. Rate cut cycles have historically acted as powerful near-term catalysts for US400 outperformance, as declining financing costs flow through more directly and quickly to mid-cap income statements than to investment-grade large-cap issuers that can lock in fixed-rate debt at scale. Traders positioning for an easing monetary cycle should consider US400 as a leveraged expression of that macro thesis relative to the S&P 500.
Sector Concentration and Leading Indicators
Industrials, Financials, and Information Technology collectively represent the largest sector weights within the S&P MidCap 400, creating meaningful concentration risk across three distinct economic cycles. Industrials exposure links US400 performance to manufacturing activity — making the ISM Manufacturing PMI a critical leading indicator. Financials exposure, particularly through regional banks, ties index earnings to credit quality trends, net interest margins, and loan growth dynamics. Information Technology exposure creates sensitivity to enterprise software spending cycles. Traders monitoring US400 should track these three indicator sets as early-warning signals for index-level earnings revisions.
Key Risk Factors
Several risk factors are specific to US400 and must be assessed alongside the structural advantages described above.
Reconstitution volatility: As demonstrated by the April 9, 2026 addition of DigitalOcean Holdings and deletion of Casey's General Stores, index reconstitution events create mechanical buying and selling pressure in individual constituents, amplifying short-term price dislocations around announcement dates.
Liquidity risk during selloffs: Individual S&P MidCap 400 constituents carry meaningfully lower trading liquidity than S&P 500 names, which can amplify volatility during broad market stress events as passive ETF outflows force selling into thinner order books.
Macro valuation backdrop: As of April 2026, the broader U.S. equity market carries an elevated valuation signal. According to Lake Ridge Bank's April 2026 market commentary, the forward market price-to-earnings ratio stands at 19.8x versus a 30-year average of 17.2x, while the Buffett Indicator — market capitalization to GDP — sits at 216.96%, well above its historical range of 111%–135%. These aggregate signals do not preclude further mid-cap outperformance in the near term, but they do indicate that the margin of safety at the index level is compressed relative to historical norms.
| Risk Factor | Implication for US400 Traders |
|---|---|
| Index reconstitution volatility | Monitor S&P announcement dates for short-term dislocation opportunities |
| Constituent liquidity | Widen volatility expectations during broad selloff episodes |
| Forward P/E at 19.8x vs. 17.2x avg. | Earnings delivery critical to sustaining current multiples |
| Buffett Indicator at 216.96% | Macro mean-reversion risk elevated; position sizing discipline required |
| Floating-rate debt sensitivity | Rate trajectory changes can rapidly reprice mid-cap earnings expectations |
For traders seeking maximum capital efficiency when expressing a view on US400, CoinUnited.io offers leveraged exposure to the index with zero trading fees — allowing precise tactical positioning around earnings cycles, Fed decisions, and reconstitution events without the cost drag that erodes returns in directional trades.
US400 vs. S&P 500 & Russell Midcap: How Does It Compare?
The S&P MidCap 400 Index occupies a strategically distinct position in the U.S. equity landscape — offering meaningfully different return profiles, index construction methodology, and institutional characteristics compared to both the S&P 500 and the Russell Midcap Index, making it an essential benchmark for traders seeking differentiated domestic equity exposure.
Performance Divergence: US400 vs. S&P 500 (US500)
The most compelling near-term illustration of mid-cap differentiation is the 2026 year-to-date performance gap. According to Franklin Templeton's Global Markets Desk, through April 9, 2026, the S&P MidCap 400 returned +7.31% year-to-date, while the S&P 500 posted a near-flat result of approximately +0.01% over the same period. This divergence underscores a structural dynamic that frequently emerges during periods of mega-cap concentration risk: when market returns become increasingly dependent on a narrow cluster of large-cap technology names, mid-cap indices with broader sector diversification and greater domestic revenue exposure can deliver meaningful alpha.
The contrast extends to the full 2025 calendar year as well. According to TradingKey Analysis, S&P 500 Growth stocks returned 19.9% and S&P 500 Value returned 12.3% in 2025 — performance heavily skewed by mega-cap dominance within those segments. By comparison, the S&P MidCap 400's growth-value spread was remarkably compressed, with Growth returning 8.1% and Value returning 7.8% according to TradingKey Analysis, indicating a more balanced and internally consistent mid-cap return profile less subject to style concentration distortions.
Methodology Differences: US400 vs. Russell Midcap
The Russell Midcap Index is the S&P MidCap 400's primary institutional competitor, but the two benchmarks differ fundamentally in construction philosophy. The Russell Midcap comprises approximately 800 companies — specifically the bottom 800 by market capitalization within the Russell 1000 — making it a strictly size-defined universe with a significantly broader constituent base than the S&P 400's precisely defined 400-company roster.
The methodology divergence carries practical implications for index quality. The Russell family reconstitutes annually each June, a predictable calendar-driven event that creates well-documented arbitrage windows as passive vehicles must simultaneously adjust large blocks of holdings. The S&P MidCap 400, by contrast, reconstitutes on an ongoing, event-driven basis with an embedded profitability screen — candidates must demonstrate positive as-reported earnings — which systematically filters out cash-burning or pre-revenue companies that can inflate volatility and drag returns in purely size-based indices. This quality screen is a key structural advantage for investors prioritizing constituent integrity over sheer breadth.
AUM and Passive Tracking Infrastructure
While detailed AUM comparisons were not available in current research data, both index families command substantial passive tracking bases, with major ETF vehicles including the SPDR S&P 400 Mid Cap ETF (MDY) and iShares products drawing significant institutional flows. The SPDR S&P 400 US Mid Cap ETF tracked by Morningstar carries a fund size of approximately $4.1 billion in its European-listed format. The depth of this passive infrastructure ensures tight bid-ask spreads and high intraday liquidity for traders accessing US400 exposure via index CFDs — a critical practical consideration when entering and exiting positions in size.
Composite Coverage and Structural Significance
The S&P MidCap 400 forms part of the S&P Composite 1500, alongside the S&P 500 and S&P SmallCap 600, a trio that collectively covers approximately 90% of U.S. equity market capitalization. This positioning makes US400 an indispensable component for investors constructing complete domestic equity exposure beyond the mega-cap universe. As IndexBox noted in March 2026, small and mid-cap equities outperformed large-caps by approximately 4% year-to-date through March 10, 2026, reflecting a broader rotation dynamic that structurally favors the mid-cap tier during phases of large-cap valuation stress — a context particularly relevant given that the forward P/E ratio for the broader market stood at 19.8x against a 30-year average of 17.2x, according to Lake Ridge Bank analysis from April 2026.
For traders on CoinUnited.io, this performance differentiation between US400 and its benchmarks is not merely academic — it represents actionable divergence that can be expressed efficiently through leveraged index CFD positions with zero trading fees.
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Trading US400 on CoinUnited.io: CFD Mechanics, Leverage & Strategies
Trading the S&P MidCap 400 Index (US400) as a Contract for Difference (CFD) on CoinUnited.io gives market participants direct, capital-efficient exposure to mid-cap U.S. equity performance — without owning the underlying basket of 400 stocks. A CFD is a derivative contract in which the buyer and seller agree to exchange the difference in the asset's value between the opening and closing of a trade, meaning traders capture index gains and losses in full without the operational complexity of replicating a 400-stock portfolio.
CFD Mechanics and Leverage on CoinUnited.io
CoinUnited.io offers US400 CFDs with up to 500x leverage and zero trading fees — a structural advantage over traditional equity platforms where index exposure typically requires ETF commissions, management fees, or futures margin requirements with far lower leverage ratios. The capital efficiency of this model is illustrated in straightforward arithmetic: a $200 margin deposit at 500x leverage controls $100,000 of notional US400 exposure. Gains and losses are calculated on the full $100,000 notional — not on the $200 margin — meaning a 1% favorable index move generates a $1,000 return on a $200 deposit, a 500% return on deployed capital. Critically, the same arithmetic applies to adverse moves: a 1% decline against the position produces a $1,000 loss, fully consuming the initial margin.
This amplification effect demands precise position sizing. As of April 2026, the S&P MidCap 400 has demonstrated meaningful intraday and monthly volatility — according to Lake Ridge Bank's April 2026 market data, the index returned -5.39% in March 2026 alone. At 500x leverage, a March-scale drawdown applied to an unhedged long position would represent catastrophic capital loss. Traders employing high leverage multiples should therefore size positions such that a single adverse 1% index move does not breach a pre-defined maximum portfolio loss threshold, and should utilize guaranteed stop orders where available.
Gap Risk: The Core Structural Risk for US400 CFD Traders
Gap risk is the primary index-specific structural hazard that differentiates US400 CFD trading from continuous-market instruments like major cryptocurrency pairs. The S&P MidCap 400 references an equity index that actively trades only during U.S. equity market hours — 9:30 AM to 4:00 PM Eastern Time. Overnight developments including Federal Reserve policy signals, major constituent earnings surprises, or geopolitical shocks can cause the CFD to open substantially above or below the prior session's close. Critically, stop-loss orders placed during off-hours may be bypassed entirely when the market gaps through the trigger price, exposing leveraged positions to outsized losses before the order can execute.
Practical gap risk management for US400 traders includes: reducing position size ahead of high-risk overnight events (Fed decision nights, major macro data releases), using guaranteed stop-loss products where slippage protection is contractually assured, and avoiding maximum-leverage positions held through extended market closures such as long weekends.
Reconstitution Event Trading: A US400-Specific Strategy
Index reconstitution events create quantifiable, time-bounded demand imbalances that experienced CFD traders can position around. When S&P Dow Jones Indices announces an addition to the S&P MidCap 400, passive ETFs and index-tracking mutual funds benchmarked to the index must purchase the newly added stock before the effective date. According to April 2026 data, the April 9, 2026 addition of DigitalOcean Holdings (NYSE: DOCN) — promoted from the S&P SmallCap 600 following M&A-driven cascade adjustments — is a recent example of this mechanism in action. Traders using US400 CFDs can position ahead of such announcements to capture the mechanical-buying-driven index adjustment impact, though the precise magnitude and duration of these effects vary with the constituent's index weight and available float.
Sector Rotation as a Directional Bias Framework
Because the S&P MidCap 400 carries heavy representation in Industrials, Financials, and Information Technology, directional bias for US400 CFD trades should integrate sector-level leading indicators. Traders can monitor the ISM Manufacturing PMI as an Industrials proxy, regional bank net interest margin trends as a Financials proxy, and enterprise IT spending surveys as a Technology proxy. When all three simultaneously show improvement, historical patterns suggest US400 may outperform large-cap peers — a macro-driven setup well-suited to medium-duration CFD long positions with moderate leverage.
Hypothetical P&L Table: 500x Leverage on US400
| Margin Deposit | Leverage | Notional Exposure | Index Move | P&L |
|---|---|---|---|---|
| $200 | 500x | $100,000 | +1% | +$1,000 |
| $200 | 500x | $100,000 | -1% | -$1,000 |
| $500 | 500x | $250,000 | +0.5% | +$1,250 |
| $500 | 500x | $250,000 | -1% | -$2,500 |
*All figures are hypothetical illustrations of leverage mechanics. Past index performance does not guarantee future results. CFD trading involves significant risk of loss.*
As of April 2026, the combination of zero trading fees, up to 500x leverage, and CFD flexibility makes CoinUnited.io a structurally distinctive venue for expressing directional views on mid-cap U.S. equity performance — provided traders anchor every position to rigorous risk management proportional to the index's demonstrated volatility profile.
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Frequently Asked Questions
The S&P MidCap 400 Index is a market capitalization-weighted benchmark tracking 400 mid-size U.S. companies, sitting between the large-cap S&P 500 and small-cap S&P 600 in the S&P family of indices. While the S&P 500 captures the largest U.S. corporations — household names with massive global footprints — the MidCap 400 focuses on companies that have grown beyond startup scale but retain significant expansion potential. This positioning creates a meaningfully different return and risk profile. Mid-cap companies tend to be more nimble than large caps, often growing revenues faster, but they also carry greater sensitivity to domestic economic conditions and credit market tightness. The index serves as a critical barometer for mid-sized U.S. enterprises and attracts substantial institutional capital through passive ETFs and mutual funds, with dedicated vehicles like the SPDR S&P 400 US Mid Cap ETF holding approximately $4.1 billion in assets.
Disclaimers & References
Important Risk Disclaimer
All S&P MidCap 400 Index price predictions and forecasts presented on this platform are purely for informational and educational purposes. They do not constitute financial advice, investment recommendations, or guidance of any kind.
Cryptocurrency markets are highly volatile and unpredictable. Past performance is not indicative of future results. The predictions shown are based on mathematical models, historical data analysis, and various technical indicators, but cannot account for unforeseen market events, regulatory changes, or other external factors.
Users should conduct their own research and consult with qualified financial professionals before making any investment decisions. The creators and operators of this platform assume no responsibility for any financial losses or other damages that may result from reliance on the information provided.
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Methodology Overview
Our S&P MidCap 400 Index price predictions utilize a multi-factor approach combining:
- Technical analysis (moving averages, oscillators, chart patterns)
- Machine learning models (LSTM networks, regression models)
- On-chain metrics (transaction volume, active addresses, exchange flows)
- Sentiment analysis (social media, news, crowd psychology)
- Macro factors (inflation, interest rates, correlation with traditional markets)
Last methodology review:
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US400
S&P MidCap 400 Index
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