TORONTO—Investors have punished Research In Motion Ltd. for the better part of a year for a series of delays in launching its next BlackBerrys, devices the company says will make it competitive once again with smartphone leaders Apple Inc. and Samsung Corp.

But suddenly, a new bout of stock-market optimism, fueled by a series of bullish reports about the phones' prospects, is buoying RIM shares. On Monday, RIM stock rose 32 cents, or 2.74%, to $11.98 a share, in New York. That caps a 30-day rally during which the stock has risen 55%. In the past three months, RIM shares are up 70%.

Earlier this month, RIM said it would introduce two phones, powered by a new operating system called BlackBerry 10, on Jan. 30. The Waterloo, Ontario, company hasn't provided many other details, including when the devices will hit store shelves, how they will be priced and which carriers will offer them.

RIM has been showing prototypes of the new phones to customers, reporters and analysts. It has also shipped the devices to some 50 carriers, who are now testing them to make sure they will work seamlessly on their networks—a critical step in any new smartphone rollout. RIM Chief Executive Thorsten Heins has said carriers have embraced the new device, though so far the carriers haven't commented publicly on their testing.

Still, several analysts who have seen RIM's new operating system are giving it positive reviews. Some are citing their own conversations with carriers. In the wake of these reviews, many are revising earlier, pessimistic forecasts that RIM will continue to bleed market share and might start seeing declines in global subscribers.