Updated

Research In Motion Ltd. (RIMM) reported a 57 percent jump in its second-quarter profit on Wednesday as surging demand for its popular BlackBerry (search) wireless e-mail device drove sales higher.

But its stock fell in after-hours trading despite an improved third-quarter sales outlook and revenue and profit forecasts that were in line with analyst expectations.

One analyst said there may have been some disappointment with forecasts for subscriber additions. RIM said it expects to add 680,000 to 710,000 subscribers in the third quarter, and between 775,000 and 825,000 in the fourth.

RIM shares fell to $74.70 on the electronic Inet brokerage system from their close of $77.25 on Nasdaq. The stock closed down 49 Canadian cents at C$90.42 in Toronto.

RIM reported net income rose to $111.1 million, or 56 cents a share, in the quarter ended August 27, from $70.6 million, or 36 cents per share, a year earlier.

BlackBerry subscribers increased by 620,000 from the first quarter to reach about 3.65 million, more than double the 1.657 million subscribers RIM had a year earlier.

Adjusted to exclude an inventory writedown and other items, RIM said its net income was $120.2 million, or 61 cents a share. Revenue at the Waterloo, Ontario-based firm rose 58 percent to $490.1 million.

Analysts had expected a profit of 61 cents a share before exceptional items, on revenues of $487.1 million, according to Reuters Estimates.

RIM had forecast second-quarter revenue of between $465 million to $490 million and adjusted earnings in the range of 57 and 63 cents.

It had also forecast second-quarter subscriber additions of between 620,000 and 650,000.

RIM increased its revenue forecast for the third quarter to a range of $540 million to $570 million. The previous forecast for third-quarter revenues was $525 million to $550 million.

It continues to see adjusted third-quarter earnings per diluted share in the range of 62 to 68 cents.

Analysts forecast a third-quarter adjusted profit per share of 66 cents on revenues of $545 million.

RIM introduced a fourth-quarter forecast for revenue of $590 million to $620 million and adjusted earnings per share in the range of 74 to 81 cents per diluted share.

This compared with analyst expectations of a fourth-quarter adjusted profit per share of 72 cents on revenues of $584.2 million.