S&P 500 Overall Performance (YTD 2025)

As of the most recent market close, the S&P 500 has returned roughly +17.33% in price-only terms in 2025 (with total return — including dividends — near +18.77%).

This strong performance masks a common market pattern seen in years when a handful of stocks dominate gains: the headline index rises, but most of the breadth is narrow. In other words, most of the gain comes from a smaller group of strong performers.

Sector Performance Context

While not all investors track sector breakdowns religiously, sector performance sets the backdrop for the stock-level action.

In 2025 investors have seen:

Large cap tech and communication names driving the bulk of returns, often buoyed by continued enthusiasm in AI and cloud growth.

Rotation seen at different points toward cyclical sectors like financials and industrials (especially mid-year), as markets adjust to interest rate changes and macro cues.

Sector performance statistics vary across sources, but the consistent theme reported throughout 2025 is tech remaining a cornerstone of gains, with value and cyclical stocks playing a smaller supporting role.

Top 20 Stock Performers — YTD 2025

Among the 500 companies in the S&P 500, a relatively small set of stocks delivered exceptional price returns in 2025:

Bottom 20 Stock Performers — YTD 2025

At the opposite end of the spectrum, some stocks lagged meaningfully: many of these also appeared in sector categories that underperformed relative to the S&P.

Representative bottom performers included:

The Trade Desk (TTD)

Fiserv (FISV)

Alexandria Real Estate Equities (ARE)

Gartner (IT)

Deckers (DECK)

Lululemon (LULU) ¬ + others down significantly on the year.

Note: these names often had much smaller market cap weightings, so their poor returns did not proportionally drag the index nearly as much as the top winners lifted it.

Top 20 Contributors to the S&P 500

In cap-weighted indices like the S&P 500, contribution to index return depends both on how much a stock returned and how large it is in the index.

Using company weights from Slickcharts and the YTD returns, we computed contributions (in percentage points) as:

Key insight: A few stocks delivered extraordinary returns — well into the triple digits — vastly outpacing the broader index.

Bottom 20 Detractors

Likewise, we compiled a set of the bottom 20 in terms of contribution to index return. These combine poor YTD performance with smaller weights, yielding contributions like:

The Trade Desk (TTD) — contribution around −0.23 ppt

Fiserv (FISV) — −0.15 ppt

UnitedHealth (UNH) — −0.15 ppt

Constellation Brands (STZ) — ~ −0.10 ppt and others

Individually, these detractors’ weights and returns result in only modest negative contributions relative to the massive positive contributions of the top 20.

What If You Exclude the Top & Bottom Movers?

This is where contribution analysis gets really illuminating:

📌 Baseline S&P 500 Return (YTD, price)

+17.33% — this reflects the entire index’s price return through late 2025. Slickcharts

📌 Excluding the Top 20 Contributors

Subtracting the +14.27 ppt from the total:

→ S&P 500 excluding top 20 = ~+3.06%

This tells us that if you strip out the biggest winners, the rest of the market — the remaining ~480 stocks — produced only a modest gain on the order of ~3% for the year.

📌 Excluding the Bottom 20 Contributors

Excluding the bottom detractors removes a small source of drag:

→ This raises the headline slightly (indicative analysis in the earlier compute suggested a small <1ppt drag).

📌 Excluding Both Top & Bottom 20

Taking out both extremes still leaves the bulk of the market with a small positive return — reflecting that the middle of the index has been drifting upward but nowhere near as fast as the market cap leaders.

What Investors Can Learn from This

1. Market Strength ≠ Broad Strength

A +17.33% headline index return might make it feel like most stocks are participating — but the majority of gains were driven by a concentrated group of names.

2. Top-heavy leadership can amplify volatility

When a few mega-caps contribute most of the returns, a correction in any of them can disproportionately affect the headline index. This can lead to outsized volatility even if the broader market is stable.

3. Sector dynamics matter

Tech and related sectors tend to house the stocks with the largest weights — so they disproportionately influence headline returns. Rotation into or out of these sectors can materially shift index performance even if many stocks are flat.

4. Breadth analysis is crucial

Tracking the contribution dispersion (how much is driven by a few versus the many) gives a more nuanced read on market tone. An index rally driven by broad participation is generally healthier than a rally driven by a handful of names.

Bottom Line

In 2025, the S&P 500’s strong YTD performance masks a highly concentrated leadership core. A small group of high-return stocks — many of which are large caps — explain most of the gains. Excluding those stocks reveals that the broader market’s contribution has been subtle by comparison.

This pattern of narrow breadth has important implications for portfolio construction, risk management, and how we interpret headline index returns — especially in markets driven by innovation-led growth themes such as AI.