You’ve got to hand it to the stock market’s bulls. They’re persistent. Stock prices tumbled in the early going today, on three pieces of disappointing news. Jobless claims came in high, construction spending was down — and then, the nation’s purchasing managers reported an unexpected drop in their closely watched manufacturing index, to its lowest level since November 2001.

Are the stock market’s bulls finally weakening? This morning’s downturn in the major indexes could be sending an important message.