WATERLOO, Ont. -- BlackBerry Ltd. shares fell in after-hours trading after the cybersecurity technology and automotive software company reported a US$315-million loss and disappointing revenue for its fourth-quarter.

The Ontario-based company's shares traded at US$8.87, down 47 cents from the official close on the New York Stock Exchange.

That was far below a brief mid-quarter surge in BlackBerry stock prices, which traded above US$25 for the first time in years in January, despite the absence of news.

The stock pop appeared to be related to an unusual trading frenzy surrounding GameStop and other companies.

Executive chairman John Chen told analysts in a conference call Tuesday afternoon that BlackBerry continued to negotiate a previously announced possible sale of some of its patent portfolio, but there was no definitive agreement.

Earlier Tuesday, BlackBerry said that it had a net loss equal to a loss of 56 U.S. cents per share, compared with a loss of US$41 million or seven cents per share a year earlier.

On an adjusted basis, BlackBerry recorded a profit of three U.S. cents per share.

Quarterly revenue for the Waterloo, Ont.-based technology company, which reports its results in U.S. currency, was US$210 million, down from US$282 million a year earlier.

BlackBerry also announced adjusted revenue of US$215 million, down from US$291 million a year earlier.

Analysts had estimated three U.S. cents per share of adjusted earnings with US$248.14 million of revenue for the three months ended Feb. 28, according to financial data firm Refinitiv.