Underneath the Hood
While the S&P 500 treaded water (down 0.50%) in the month of September, it was not your average run of the mill month under the surface. For starters, the bond market was far from boring, so stay with us here, bonds are not sexy. Here goes...
September was among the worst months for U.S. bonds in a generation. The Bloomberg U.S. Aggregate Bond Index, the broad benchmark for the U.S. investment grade bond market, fell 2.6% for the month. Why?
The Federal Reserve raised the federal funds rate by 25 basis points at its September meeting, to 3.75%–4.00%, the first hike since 2023. The vote was unanimous. The hike itself was widely expected, but the reaction was not. Chairman Kevin Warsh described the move as removing a dose of accommodation without saying whether it marked a lasting change in policy, and bond markets sold off. The 10 year Treasury yield rose 82 basis points in the third quarter, 54 of them in September, and ended the month at 5.29%, its highest level since 2002. The 30 year yield reached levels last seen in 2007. 30 year mortgage rates, which are heavily influenced by 10 year US Treasury yields, topped 7% by the end of September. The trend has continued in October, as the average rate increased to 7.40%.
How rare was it? A 2.6% monthly loss is a nonevent for stocks, which routinely swing that much. For bonds, it is a rare and significant move. Over the past 30 years, only five months have been worse.
Whether or not you understood all of this, we're simply saying it was a rough month for the bond market.
Why yields rose
Several pressures came together in September:
- Energy and inflation. Yields have risen since the Iran conflict began, tracking Brent crude, which again topped $100 a barrel in September. Everyone reading this is feeling this at the pump.
- A strong economy. Resilient growth and full employment also contributed.
- Fiscal and supply concerns. Growing Deficits and heavy AI related debt issuance added to the upward pressure.
Let’s look at it from a glass half full perspective.
Simple...higher starting yields mean higher expected returns. The price declines hurt in the short run, but newly invested money now earns far more income than it did a few years ago.
How stocks reacted
As mentioned earlier, the S&P 500 slipped less than 1% in September and finished the month still holding YTD gains over 12%, but that average hid a wide split underneath. Only technology gained in September and all other ten sectors fell, and the rate sensitive areas were among the hardest hit.
The S&P 500 gained 3.8%, but the gains came almost entirely from a handful of names. As crazy as it sounds, a total of 5 stocks (Microsoft, Meta, Alphabet, Apple and Nvidia) accounted for 93% of the gains since July.
Surprisingly, as of the end of September, roughly 60% of the S&P 500 stocks were in drawdowns of 20% or more. Additionally, more than a third of the index sat more than 35% from their high.
As we write this, the iShares Semiconductor ETF (SOXX) is coming off its 8th consecutive down day. The ETF has fallen more than 14% in that timeframe, erasing over $2 trillion in market cap, as higher interest rates and financing costs weighed on stocks within the semiconductor industry...regardless the fund is still up 70% YTD.
While you might take all this as bearish, it also gives us some opportunities Corporate earnings growth is expected to stay robust, albeit at a lower growth rate than in ‘26 but still above historical averages. Markets anticipate earnings to broaden to more sectors beyond a handful of mega cap tech stocks as AI advances begin to impact the bottom line of other sectors outside of technology.
With all of the uncertainty - higher interest rates, volatile oil markets, stubborn inflation, geopolitical risks and midterm elections...now is the time to stick to quality. Sector performance tends to rotate, so some of the “unloved” sectors YTD may turn.
Just because something has performed well in the past doesn't mean it'll continue to do so. That's why it's important to keep your portfolio balanced and avoid getting too caught up in short term market moves. It may sound like basic advice, but keeping a long term perspective still matters.
As always, don't hesitate to reach out if you have any questions or concerns.












