Bitcoin ETFs' biggest inflow day in 11 months, then a slide the day yields jumped

U.S. spot bitcoin ETFs took in $998.95 million on Monday, Sept. 21, their largest single day in 11 months, The Block reported, and bitcoin briefly passed $87,000. Two days later, on Sept. 23, the 10-year Treasury yield jumped 15 basis points and, CoinDesk reports, bitcoin slid back toward $83,500.

Key points

• The flows were far larger than in our last reading. Our Sept. 20 story said ETF flows did not show institutions buying the dip in size, citing The Block's weekly tally of $6.2 million net for the week to Sept. 18. The Sept. 21 session did not fit that reading. The Block (Timmy Shen, 3:44 a.m. EDT Sept. 22) reported net inflows of $998.95 million into U.S. spot bitcoin ETFs on Monday, their biggest one-day haul in 11 months, and named Oct. 6, 2025, at $1.2 billion, as the last bigger day. Citing SoSoValue, it gave BlackRock's IBIT $381.4 million, Ark and 21Shares' ARKB $289.1 million and Fidelity's FBTC $238.8 million. CoinDesk credits SoSoValue for the same $998.95 million total.
• The Block put Monday's peak price near $87,300, its highest since January 2026. The explanations on offer are analysts' views, not measurements. In The Block's report, Presto Research's Min Jung said no single event stood out and that several forces overlapped, ETF buying among them. ViaBTC's Jeff Ko described the move as largely technical, saying bitcoin got through the $82,000 mark where it had been held back.
• Yields jumped on Sept. 23, the day bitcoin fell. Treasury's par yield table shows the 10-year at 4.96% on Sept. 21 and Sept. 22, 5.11% on Sept. 23 and 5.18% on Sept. 24. A basis point is one hundredth of a percentage point, so the Sept. 23 change is 15. CoinDesk (Omkar Godbole, published Sept. 24) reports that the 10-year jumped 15 basis points on Wednesday, and that the MOVE index of expected bond-market volatility rose 21% that day. It ties bitcoin's slide from about $87,200 to about $83,500 partly to that rise in bond volatility, and adds that the market may have been ready to fall back after its run.
• CoinDesk's own reading is mixed. Its subheadline says bitcoin has not tracked rising yields over the long term, while a jump in bond-market swings could weigh on crypto in the near term. By CoinDesk's analysis, bitcoin's day-to-day returns have moved with the 10-year's daily changes at a correlation of -0.18 over 90 days and -0.03 over one year, and CoinDesk calls the 90-day figure close to zero. A correlation of 0 means no consistent link; -1 would mean perfectly opposite moves. CoinDesk says its 90-day figure comes from data it analyzed itself. Bitget Wallet's Lacie Zhang told CoinDesk the near-zero correlation suggests bitcoin is "not simply trading as a duration or rates asset."
• Crypto is still well under its record. Yahoo Finance (Ines Ferré, 8:41 a.m. EDT Sept. 22) put the total crypto market value at $2.94 trillion on Monday, on a chart it credits to CoinMarketCap, about 30% below its October record. CoinDesk gives bitcoin's record as $126,000 last October.

Why it matters

Our Sept. 20 reading of the flows described one week and did not carry forward. A single day of about $1 billion shows that a lot of money arrived on Sept. 21; it does not say what that money will do over the weeks after. The yield link needs the same care in the other direction. On Sept. 23 a 15 basis point jump in the 10-year came on a day bitcoin fell, but CoinDesk's longer-window correlations are close to zero, and one day cannot confirm or refute a relationship measured over 90 days or a year. CoinDesk itself allows that the market may have been ready to fall back after its run. The explanations above are analysts' views, not measurements, and none of these figures is a recommendation or a forecast.

This is an AI-written summary of the sources credited above and linked in the text, read and edited by Nicholas before publishing. The facts and the quoted phrase belong to those sources; the wording is ours. Read the original.