* Adjusted 1st-quarter revenue of $244 mln misses estimates
* Expects software, services growth in 2nd half -CEO
* U.S.- and Canada-listed shares both fall more than 10 pct (Adds comments from BlackBerry CEO)
By Narottam Medhora and Jim Finkle
WATERLOO, Ontario, June 23 (Reuters) - BlackBerry Ltd posted quarterly revenue that missed analysts' forecasts due to an unexpected sales decline, pushing shares down as much as 13 percent, which would be their biggest one-day drop in more than two years.
The company reported that software and professional sales fell 4.7 percent to $101 million during the first quarter.
Investors pay close attention to that category because growth of high-margin software sales is at the heart of Chief Executive Officer John Chen's turnaround strategy for the company. Its stock had gained about 60 percent over the past quarter on expectations that sales of new software products are starting to take off.
"This is a big disappointment for the stock and likely to cast a pall on the sustainability of the turnaround," said Tim Ghriskey, chief investment officer with Solaris Asset Management who helps manage $1.5 billion.
The Waterloo, Ontario-based company is focused on expanding sales to automakers and other manufacturers, and expanding in cyber security market, after ceding the smartphone market to rivals including Apple Inc, Alphabet Inc's Google and Samsung Electronics Co Ltd.
Chen said at a news conference that the company had "organic growth" in software sales of 12 percent, after adjusting for deferred-revenue from an acquisition in the year-earlier quarter.
He added that the company would have to "play catch up" to meet its goal of boosting software and services revenue by 10 percent to 15 percent this year: "We intend to do that.”
Chen also said the first-quarter drop was due to a decline in professional services, which went from $27 million in the fourth quarter to "almost nothing" in the first quarter.
"A lot of the newer markets BlackBerry is trying to position around are longer-term markets ... Managing short-term, quarter-on-quarter performance in light of that trajectory is going to be a challenge," said Nick McQuire, vice president for enterprise research at CCS Insight.
BlackBerry's U.S.- and Toronto-listed shares were down about 10 percent after falling as much as 13 percent, their biggest respective one-day falls since January 2015.
The company reported revenue on adjusted basis of $244 million for the quarter ended May 31, missing analysts' estimates of $264.5 million, according to Thomson Reuters I/B/E/S.
It reported a quarterly profit of $671 million, or $1.23 per share, compared with a loss of $670 million, or $1.28 per share, a year earlier. (blck.by/2sJnsFS)
The results included a previously disclosed $940 million arbitration payment from U.S. chipmaker Qualcomm Inc.
Excluding items, the company earned 2 cents per share. Analysts on average had expected the company to break even.
The company also said it would buy back 31 million shares. (Reporting by Jim Finkle in Waterloo, Ontario; and Narottam Medhora in Bengaluru; editing by G Crosse and Lisa Shumaker)