Coinbase fell 10% and took the exchanges down with it. The banks didn't move.

Coinbase closed down 10.10% on 15 September 2026, the single worst session among all 500 names in the S&P 500 that day. The move came the same afternoon the U.S. Senate failed a cloture vote on the CLARITY Act, the crypto market-structure bill the industry had been pushing through Congress, which CNBC reported failed around mid-afternoon Eastern time.

Coinbase's market cap closed the session at $45.4 billion. Working back from the day's percentage move, that implies roughly $5.1 billion in market value came off the stock in a single session.

The vote and the slide, same afternoon

The timing lines up across outlets. CNBC's report of the cloture vote's failure was filed at 3:05pm ET. CoinDesk had Coinbase "sliding nearly 9%" in a piece filed just under an hour later. Barron's and Decrypt both followed within the next two hours, tying both Coinbase's slide and bitcoin's own decline directly to the failed vote rather than to anything company-specific. None of the coverage points to a Coinbase earnings report, guidance change, or other company news that day — the stock moved with the rest of the crypto-exposed trade.

One sector number hid two different days

Coinbase sits inside the site's Financials sector, which closed down 0.36% on a market-cap-weighted basis across 75 constituents — 22 higher, 53 lower. That modest sector-wide figure hides a split between two kinds of business inside it. Trading venues, brokers and other names with direct exposure to trading volume and retail flow fell hardest:

The sector's largest deposit-taking banks, meanwhile, barely moved:

Five of six banks above closed within a point and a quarter of flat. None of the six trading venues and brokers did.

How large a move this is for Coinbase

The site's price history puts today in context. Over the last two years of trading days, Coinbase's daily percentage move has averaged out to a standard deviation of about 4.72 percentage points. A 10.10% decline is a little over two standard deviations — a large day, though not a record for the stock. It is Coinbase's fifth-largest single-day decline in that two-year window:

Coinbase has now had five double-digit-percent single-day declines in about eighteen months. Today's is the smallest of the five, and the only one so far that coincides with a specific, dated piece of legislation rather than a broader crypto-market move.

What the map shows and doesn't

The treemap for 15 September shows Financials as a middling sector on an unremarkable day — down a little more than a third of a percent, in the middle of the pack across the S&P 500's eleven sectors. Zooming into the sector is what shows that the decline wasn't spread evenly across banking, insurance and market infrastructure. It landed on the handful of names whose business runs through trading volume and crypto-adjacent flow, on the same afternoon the bill meant to give that business regulatory clarity failed to advance.