Bitcoin miners fuel Russell 2000's 14% gap over S&P 500

Small-cap stocks beat large caps by the widest margin in two decades through June. The Russell 2000 outpaced the S&P 500 by nearly 14 percentage points in the first half of 2025. That gap, if it holds through December, would be the largest since the early 2000s.

Bitcoin miners drove a big chunk of the divergence. Bitcoin itself surged roughly 85% year-to-date through June. That rally lifted mining stocks that live inside the Russell 2000. Bit Digital jumped 627% over the period. Marathon Digital climbed 297%. Cipher Mining also posted gains of its own. These companies give traditional equity investors direct exposure to Bitcoin price moves without needing a wallet or on-chain setup.

Small-cap digital assets rallied hard too. Gaming and metaverse tokens led that leg. The pattern of the smallest, most speculative assets outperforming broader markets has historically appeared early to mid-cycle in crypto rallies, according to data from earlier in the year.

Small-cap stocks and crypto assets tend to move together, especially when liquidity is loose or sentiment improves. Both are high-beta plays. They fall harder than large caps when conditions sour. The same correlation that drove the first-half outperformance could accelerate losses if sentiment shifts.

Bitcoin mining stocks effectively turned the Russell 2000 into a partial proxy for Bitcoin exposure. For institutional investors who cannot hold BTC directly, these equities offer a familiar vehicle with similar directional characteristics.

The trade to watch is Marathon Digital and its peers. If they start rolling over, the small-cap momentum trade – and potentially the broader crypto rally – may be running out of steam.