New Delhi, Sept. 8 -- If Labor Day marks the unofficial end of summer, then the stock market may soon make it official. The September storm clouds are gathering.

Oil prices are flirting with $100 a barrel again, more than six months into the Iran conflict. It's a dalliance equities could really do without.

Stocks have ignored elevated oil prices up to now-the S&P 500 is up 12% since the Iran conflict began even as Brent crude prices have jumped 35%. That might not last given that inflation will dictate whether, and how often, the Federal Reserve hikes rates in the months ahead.

The Dow is the worst hit index to start the trading week, but that's largely down to Amgen, which slumped after its Swiss rival Novartis released disappointing ...