Shares in Research In Motion (RIM) were down 5 percent at one point this morning after the BlackBerry maker yesterday reported lower-than-expected shipments in the fourth quarter.

RIM shipped about 10.5 million devices in the fourth quarter, down from the consensus expectation of 11 million. About 4.9 million net new BlackBerry subscriber accounts were added in the quarter.

In a conference call with analysts, co-CEO Jim Balsillie spent much of the time defending the company’s competitive situation. The lower-than-expected unit shipment was blamed primarily on a one-time inventory adjustment at a carrier customer, which some analysts surmised was for the Storm 2 at Verizon Wireless.

While RIM continues to see growth internationally, the North American market is “doing very, very well,” Balsillie said. He wouldn’t speculate on what will happen if Verizon Wireless does get a CDMA version of the iPhone as The Wall Street Journal reported earlier this week.

For the fiscal year, BlackBerry smartphone shipments grew more than 40 percent over the prior fiscal year, to 37 million. Revenue for the fourth quarter of fiscal 2010 was $4.08 billion, up 18 percent from $3.46 billion in the same quarter of last year and up 4 percent from $3.92 billion in the previous quarter.

At the end of the quarter, the total BlackBerry subscriber account base was more than 41 million.

Balsillie said the company expects strong shipments and earnings growth in the first fiscal quarter and is excited about the products and services in the pipeline for the coming year.