Small Caps Sink as 10-Year Yield Hits 5.17%, IWM Loses $3.3B

The iShares Russell 2000 ETF (IWM), the largest fund tracking U.S. small-cap stocks, lost $3.3 billion to investor withdrawals in a single week as the 10-year Treasury yield climbed to 5.17% on September 24, its highest level since 2007. That bond-market surge has erased a big chunk of small caps' 2026 lead over large caps, and options traders are now paying up for insurance against further declines.

What happened

Small-cap stocks started September as the year's best-performing major U.S. equity segment. CNBC reported that at the start of the month the Russell 2000 was up 20% year to date, ahead of the S&P 500's 13% gain and the Nasdaq-100's 17% advance. By September 24, CNBC reported the Russell 2000's year-to-date gain had narrowed to 14%, while the S&P 500 and Nasdaq-100 stood at 20% and 12%, respectively, on that same intraday snapshot. CNBC attributed the reversal to "higher interest-rates and falling bond prices."

The fund-flow data lines up with that shift. Benzinga, citing a post from The Kobeissi Letter, reported that IWM recorded $3.3 billion in outflows in the week before September 26, its second-largest weekly withdrawal of 2026 and third-largest in nine years, and that the Russell 2000 had fallen 7.3% since mid-August to its lowest level since June 10. The same report noted the S&P 500 had outperformed the Russell 2000 for five straight weeks, which would become the longest such streak in eight years if it extended a sixth week.

Not every outlet's same-week snapshot matches exactly. InvestorPlace, drawing on FactSet data through September 21 (three days before CNBC's figures), put the Russell 2000 at a 15.9% year-to-date gain versus 13.4% for the S&P 500 — the opposite ranking from CNBC's September 24 numbers. The gap is plausibly explained by timing: the bond market sold off sharply in the three trading days between those snapshots, including a weak September 23 auction of five-year Treasury notes that priced at a 5.033% yield, the highest since 2006, according to T. Rowe Price's markets update. Index-level comparisons over a holding period this short can swing significantly depending on the exact day and hour they're pulled.

Why higher yields hit small companies harder

The mechanism traders point to is balance-sheet exposure to interest rates. CNBC quoted Kevin Gordon, head of macro research and strategy at the Schwab Center for Financial Research, saying "small caps have had a more difficult time adjusting to the Fed's hawkish turn and continued increase in rates at the long end, evidenced by the fact that their negative correlation to the 10-year Treasury yield is two times that of large caps." Small-cap companies tend to carry more floating-rate and shorter-maturity debt that they must refinance more often, so a jump in benchmark yields raises their borrowing costs faster than it does for large caps with longer-dated, fixed-rate bonds. The Motley Fool, citing Goldman Sachs, reported that about 32% of Russell 2000 companies hold floating-rate debt, compared with just 6% of S&P 500 companies — a structural difference that helps explain why the Russell's price correlation to Treasury bond prices is now nearly double the S&P 500's, per CNBC's data.

That doesn't mean every small-cap company is equally exposed. Gordon also told CNBC that "from a broader perspective, I wouldn't discount the still-strong fundamentals that some small caps are showing," pointing to improving purchasing managers' index readings and what he called solid forward earnings estimates for the group. In other words, the correlation data describes how small-cap stock prices are trading right now relative to bonds — it does not by itself say whether the underlying businesses are financially weaker.

What options traders are betting on

Options activity in IWM on September 24 leaned bearish. CNBC reported that of $322 million in total premium traded in the ETF that day, roughly $100 million was likely spent buying puts (contracts that profit if the price falls) versus about $50 million on calls, according to SpotGamma data, though some large sellers of puts were also active. The four most heavily traded contracts by volume were all puts: same-day 280- and 281-strike puts combined for more than 120,000 trades, and the next-most-popular contract was a 269-strike put expiring October 16 that needs roughly a 4% additional selloff in IWM to turn a profit. That positioning shows traders were paying for near-term protection and placing directional bets on further weakness, not that a 4% drop is expected to happen.

What remains uncertain

The reporting establishes a clear, data-backed divergence between small- and large-cap stock performance coinciding with a bond-market selloff, plus fund outflows and bearish options positioning. What it does not establish is how long the divergence lasts or whether it reverses if yields stabilize; Gordon's comments suggest earnings fundamentals could support a rebound, but that is his stated view, not a forecast confirmed by subsequent data. The bond-side pressure also has its own open questions: a weak September 23 five-year note auction and a September 24 seven-year note auction that priced 7 basis points above pre-auction trading levels, both reported by T. Rowe Price, suggest reduced demand from buyers, but neither report identifies which category of investor pulled back or why.