Shares of Research In Motion stumbled Wednesday after the maker of BlackBerry smartphones said it expected gross margins and earnings per share to be at the low end of its previous guidance.

RIM shares tumbled $9.29, or 16.25 percent, to $47.72 in late-morning trading.

The company said it expected fiscal fourth-quarter revenue to come in around the midpoint of its previously announced range of $3.3 billlion to $3.5 billion, but that earnings would be at the lower end of its $0.83 to $0.91 cents range.

RIM attributed its revised outlook in part to an increased ratio of new subscriber sales versus higher-margin upgrade and replacement sales. The company said it expects net subscriber additions for the quarter ending February 28 to be 20 percent higher than the 2.9 million it forecast on December 18.

JMP Securities analyst Samuel Wilson said the selloff was overreacting to RIM’s announcement and reading “inferences into the exact words.”

In any case, he said, Wall Street analysts already had adjusted their earnings expectations toward the low end of RIM’s range.

“This is where the consensus was already,” he said. Thirty-seven analysts polled by Thomson Financial on average expect RIM to earn $0.85 per share, with a high estimate of $0.93 and a low estimate of $0.69.

Before the holiday shopping season, Blackberry introduced several new models, including the touchscreen Storm on the Verizon Wireless network and the Bold on AT&T Wireless that helped the smartphone category grab an increasingly large slice of the mobile phone market.

Market tracker IDC predicts that in 2009, smartphone shipments will increase 8.9 percent globally and 3.1 percent in the United States, while sales of other mobile phones will fall 3.5 percent worldwide and 11.5 percent domestically.