Oil prices drop more than $10 a barrel in selloff that follows big drop in US stock prices

Oil prices tumbled Tuesday as U.S. stocks sold off amid worries about America's economic health.

Prices dropped more than $10 a barrel from their highest point of the day. At midday, light, sweet crude fell $6.27 to $138.91 in an extremely volatile session.

The turnaround may not signal a lasting shift in sentiment _ prices have swung violently in recent days as they flirted with record highs. But it does underscore investor uncertainty about the sustainability of sky-high prices and their effect on the broader economy.

"They're slamming this pretty good. But remember, these $10 moves are becoming a little more commonplace," said Phil …