The September effect used to be the lazy investor’s security blanket. Sell in May, hide in August, wait for October. Very tidy. Very comforting. Also, lately, wrong.

September rose about 2% in 2024 and 3.5% in 2025. The calendar did not save anyone. It just stopped being useful.

What has actually billed us for seven months is not the almanac. It is Brent, now trading around $97 after last week’s jump, and a Strait of Hormuz that refuses to become background noise. The market has learned to live with low-intensity Hormuz risk. That is not the same thing as being numb. A waterway that used to move roughly a fifth of the world’s oil is still running on a trickle. When tankers get hit again, prices still jump. So do yields.

I wrote about that tape a few days ago, when I had the bright idea of launching a trading bot into the same mess: Of Course I Launched the Trading Bot on a Hormuz Day.

This September can still turn ugly. Not because “September always does,” but because oil is already leaning on inflation, and the Fed is no longer a one-way easing story. They held in July. Hawks dissented. When crude rips, hike odds come back. That combination is enough. You do not need a folk legend about the ninth month.

The last few days look like escalation, not drift. My unfashionable take: Washington does not look eager to climb down before the midterms on November 3. I think they will ride the tiger to the end of that calendar, midterms or not.

No victory lap. No crash call. Just the grown-up version of “this can still get expensive.”

If you still treat September as a seasonal curiosity, say so in the comments. If you are watching the strait instead of the almanac, say that too. I want to know which camp is actually managing money and which camp is just repeating an old rhyme.