An 11th hour U.S.-Iran cease-fire has triggered a spectacular rally for stocks and the opposite for oil prices.

That’s even as a lasting deal has not been agreed, with an estimated 800- plus stranded vessels in the Persian Gulf.

The worry for some is that the sharp stock rebound may be getting ahead of itself. In that camp is a senior trader at Goldman Sachs, Rich Privorotsky, who sees major risk ahead as the market tries to “move past Iran.”

In a note to clients, Privorotsky cautioned that “this isn’t a great level to chase,” with regard to the S&P 500

He noted that the index had already recouped two-thirds of losses incurred when the conflict began in late February; from its most recent record high in January, the S&P 500 was down about 5%.

Commenting that “cease-fires are fragile by definition,” Privorotsky said strikes have been seen overnight across the Gulf region despite the cease-fire. “You can hand-wave some of that as lag effects, but the disagreement around proxies (e.g. Lebanon with Israel) leaves plenty of scope for this to break,” he said.

The market will ultimately judge “actual flows through the Strait over time,” he said. “I struggle to see new highs for equities, but positioning still argues for forced buying to run its course first.”