Research in Motion is launching variations of two existing BlackBerry smartphones, the company said on Monday, and its co-chief executive hinted that much-anticipated announcements on a new operating system and browser are also on the way.

But its stock fell as the news fell short of what many investors were hoping the company would announce to counter growing competition from rivals like Apple Inc and Motorola Inc, especially in the consumer market.

RIM does not have a competing product for the retail space and that is very, very negative for anyone who's buying the stock today, said Barry Schwartz, vice-president and portfolio manager at Baskin Financial Services.

RIM unveiled the new versions of both devices on the eve of its annual Wireless Enterprise Symposium, a three-day event that officially runs from April 27-29 in Orlando, Florida.

A CDMA version of the high-end BlackBerry Bold device will ship in May to both Verizon and Sprint Nextel - two of North America's largest wireless carriers that run CDMA networks, the company said in a statement. The BlackBerry Bold is already available to carriers that operate GSM networks.

GSM and CDMA are the two main types of mobile technology used by wireless carriers across the world. CDMA lost the battle for global dominance but it still has a strong position in some markets.

The Waterloo, Ontario-based company is also taking the wraps off a new 3G version of the Pearl, which is the smallest of its range of BlackBerry devices. The new GSM device will allow for faster data downloads on newer 3G networks.

But the market was hoping for early news about an improved BlackBerry operating system and browser for navigating the Internet, which even devout fans say is not as easy to use as Apple's iPhone and Motorola's Droid.

Co-Chief Executive Jim Balsillie hinted that fellow co-CEO Mike Lazaridis could reveal more details in a presentation later on Monday as well as throughout the WES trade show.

You are going to hear a lot about our web strategy this week, Balsillie said in the opening address at the event.

I won't steal any of Mike's thunder, he said.

Analysts hope the software improvements will allow RIM to compete more effectively against the iPhone, Droid and a slew of other smartphone devices that have been nibbling away at RIM's market share.

A growing number of analysts argue that rival smartphones could keep taking market share from the BlackBerry, especially in North America, unless RIM delivers an improved operating system and browser.

Balsillie took a more optimistic view of the BlackBerry's outlook. I think the North American market will continue to grow, and grow quickly for us, he said.

Consumer-friendly enhancements, such as more powerful in-phone cameras and an easier-to-navigate display, are also in the offing, he said.

You are going to see very powerful extensions on our part. I don't think you have to be too patient either, he said.

RIM's apps store, which analysts say falls far short of Apple's applications' offering, is growing fast with downloads doubling in last 120 days, he said.

RIM on Monday also announced an upgraded version of its mobile voice system (MVS) technology, which allows for the seamless integration of a customer's office landline and BlackBerry device. The technology currently allows the two devices to work as one and a user can route all outgoing calls through his office landline device.

The latest upgrade to the MVS technology will allow users to make and receive phone calls from their BlackBerry devices over a Wi-Fi connection.

RIM's stock fell as much as 2.9 percent to C$68.50 on the Toronto Stock Exchange early on Monday. By late morning, the stock was off its lows at C$69.33, down C$1.23 or 1.7 percent.

On Nasdaq, it was down 1.8 percent at $69.37.

(Additional reporting by Claire Sibonney in Toronto; Editing by Frank McGurty)