US PMI Reached 58.4 as Treasury Yields Rose: What Happened on September 23?

The September 2026 flash US Composite PMI Output Index climbed to 58.4 from 56.0 in August. Later on September 23, a $70 billion auction of five-year Treasury notes cleared at a 5.033% high yield amid demand described as weak. The Treasury's ten-year constant-maturity yield rose from 4.96% on September 22 to 5.11% on September 23. These numbers measure different things: a business survey, a particular auction and broader secondary-market pricing. S&P Global · US Treasury · Auction coverage

The sequence of events

Time on September 23, 2026 (EDT / UTC)	Event	What it tells us
9:45 a.m. / 13:45	S&P Global released the flash US PMI. The composite output index was 58.4, up from 56.0 in August.	Business activity and cost pressures were accelerating.
About 1:00 p.m. / 17:00	The Treasury auctioned $70 billion of five-year notes at a 5.033% high yield; demand was described as weak.	The price required to place that issue with bidders.
Daily closing-market measure	The Treasury's ten-year constant-maturity yield was 5.11%, versus 4.96% the previous trading day; the 20-year measure moved from 5.33% to 5.45%.	How the market repriced other maturities.

Sources: S&P Global's flash PMI release, auction and market reporting and the Treasury's daily yield table. The Treasury's rounded 5.11% constant-maturity measure and the 5.106% benchmark-note yield reported in the market refer to different measures and precision.

Why did the PMI matter for bonds?

The jump from 56.0 to 58.4 signals faster growth in activity reported by surveyed firms; it does not mean GDP rose 58.4%. S&P Global also reported stronger hiring, rising work backlogs, longer supplier delivery times and input-cost growth near a four-year high. Stronger activity may help revenues, while persistent cost pressure may lead investors to expect interest rates to stay higher or rise further. S&P Global's analysis

That is a plausible transmission mechanism, not proof that the PMI alone caused the full move. Oil prices, Federal Reserve remarks and technical trading also shaped the day. Fed funds futures moved to imply roughly a 66% probability of an October hike, up from about 53% earlier in the day. Market-implied odds can change and do not announce a Fed decision. Market coverage

Auction yield versus ten-year market yield

The 5.033% figure was the highest accepted yield at one five-year note auction. A high yield alone does not establish weak demand: assess it against the pre-auction market level and other auction measures, such as the bid-to-cover ratio and the mix of buyers. Contemporary reporting described this sale's demand as weak. Auction coverage · TreasuryDirect auction terms

The 5.11% figure was the Treasury's ten-year constant-maturity secondary-market measure, not a yield set by a ten-year auction that day. For an existing fixed-coupon bond, a fall in market price generally raises its yield to maturity. An auction may affect neighboring maturities, but it does not mechanically set every point on the yield curve. Treasury data and methodology

How did Treasuries and US stocks respond overall?

Treasuries: yields rose across maturities, putting bond prices under pressure. The Treasury's ten-year constant-maturity yield increased from 4.96% to 5.11% on September 23, while its 20-year measure rose from 5.33% to 5.45%—about 15 and 12 basis points, respectively. For fixed-coupon bonds, rising yields generally mean falling market prices; longer-duration bonds are usually more sensitive to a given yield change. Strong PMI activity and cost pressures may have raised rate expectations, but oil prices, Fed remarks and the later five-year auction also affected pricing. The full-day move cannot be attributed to the PMI alone. US Treasury daily yields · S&P Global PMI analysis

US stocks: major indexes closed lower. The S&P 500 fell about 0.8%, the Nasdaq Composite 1.1% and the Dow Jones Industrial Average 0.7%. Higher Treasury yields can reduce the present value investors assign to future earnings, particularly for growth stocks. Strong business activity can, at the same time, support expectations for company revenue. Oil, policy expectations and company-specific developments also shaped the day's trading; the index declines do not establish that the PMI alone caused the sell-off. US market close

What could BBX readers watch?

Long-duration Treasury exposure. Five-year notes and bonds with more than 20 years to maturity have different rate sensitivities. The Treasury's 20-year yield also rose that day, but TMF and TBT seek daily leveraged or inverse results tied to a long-duration Treasury index. Their ETF returns also depend on index movements and daily resetting. BBX lists the related TMFUSDT perpetual contract and TBTUSDT perpetual contract. A contract position is neither a Treasury bond nor an ETF share and introduces margin, funding-rate and liquidation risk. The five-year auction yield cannot be used as a formula for either contract's return.

Stocks and semiconductors. Higher yields can weigh on valuations and financing conditions, while economic strength may help demand. NVIDIA (NVDA) and Micron (MU) are also affected by AI spending, memory-industry conditions and company earnings. BBX's NVDAUSDT perpetual contract and MUUSDT perpetual contract are contract pages, not a way to own NVDA or MU shares. Broad US stocks weakened on the day; that does not establish these two names' exact daily returns or attribute any move solely to the PMI. Market coverage

Sources: S&P Global PMI analysis; original flash PMI release; US Treasury daily yields; auction and market report; TreasuryDirect auction FAQ.