Reaching for one more weapon in its battle against Microsoft, IBM Monday launched a $3.3 billion hostile takeover bid of Lotus Development Corp., the third-largestsoftware company in the world.

If successful, the deal could scramble the software landscape and force Microsoft to rethink its competitive strategy.

Then again, Microsoft could win no matter what happens.

Lotus stock soared Monday to $61.43 3/4, up $28.93 3/4 from Friday’s close. IBM is offering $60 a share for Lotus, which has about 55 million outstanding shares. Lotus said it is studying the surprise offer.

The announcement was one more indication of the fierceness with which IBM is trying to take back the lead in personal computing. The purchase would give IBM a chance to turn the strategic tables on Microsoft, which uses its popular products to lure customers to its other programs.

“IBM has been miffed by all the industry attention to Microsoft and its control of the de facto standard in the software industry,” said Karl Wong, PC software analyst at market researcher at Dataquest.

By acquiring Lotus, IBM would gain Lotus’ famed 1-2-3 spreadsheet program and its cc:Mail electronic mail program, but the real gem would be Lotus Notes, a young product that allows people on networked computers to work together. Microsoft so far has not made a dent in the coveted “groupware” market.

With the Lotus products, IBM’s sales force could offer a package of products priced to grab Microsoft’s business. More than half of Microsoft’s office products are sold in bundled packages called suites.

But the move could also help Microsoft by:

Distracting two competitors for months or longer, while the Redmond, Wash., giant holds customers and courts others and improves its own product line.

Putting Lotus Notes in the hands of a company with a poor recent marketing record.

Easing Justice Department antitrust pressures on Microsoft by giving it a strengthened competitor.

Microsoft had planned to acquire Intuit Inc., a maker of personal finance software, for $2.2 billion but that deal collapsed last month after the Justice Department moved to block it on antitrust grounds.

Scott McAdams, an analyst with Ragen MacKenzie in Seattle, said it would be difficult for a combined Lotus-IBM to erode Microsoft’s dominance of personal computing.

“I don’t think it ups the ante very much,” he said.

Microsoft is preparing to launch Windows 95 and is overdue to release Microsoft Exchange, viewed as a weak alternative to Notes.

Groupware, which allows people to share files, grab information and perform other tasks on a network, is regarded as one of the key new markets in personal computing. About 68 million personal computers are linked on networks, a number expected to grow rapidly.

In a personal letter to Lotus Chief Executive Jim Manzi, IBM Chief Executive Louis Gerstner Jr. made it clear the target was Notes.

“With IBM’s global marketing and sales capability, we can rapidly grow Notes’ user base and vastly increase its sales potential and acceptance as an open industry standard,” Gerstner said.

IBM stock closed down $2.62 cents Monday at $91.25.