Microsoft's CEO to officially launch Office for iPad today?

But bold moves with Office, and signifying a renewed drive to conquer the mobile arena and 'cloud' computing after years of shackling its best products to PC-centric Windows, are seen as a promising start.

"This is something that should have happened a few years ago," said J.P. Gownder, an analyst at tech research firm Forrester. "Holding Office for iPad as a hostage in the tablet war didn't work out well for them. They have to start to undo this negative behavior."

Nadella has more work to do as well on the devices side of Microsoft's business plan. Windows-powered phones are well reviewed but held only three per cent of the global smartphone market last year. Its Surface tablet, an iPad competitor, had two per cent of the tablet market, according to tech research firm Gartner. Daniel Ives, an analyst at FBR Capital Markets.

Depending what Microsoft charges for Office on the iPad, and how many of the scores of millions - and rising - iPad users adopt it, it could rake in anywhere between $840 million to $6.7 billion a year in revenue, estimates RaimoMicrosoft's $7.2 billion deal to buy the handset unit of Nokia, now delayed in closing, is unpopular with many investors who view it as a doomed defensive play to curb Google's Android's dominance in the smartphone market.

It is "an acquisition not even a mother could love," according to Nomura's Sherlund.

Wall Street will be listening for Nadella's thoughts on the Xbox, the subject of renewed spin-off talk recently, and his willingness to buy his way into cloud-based computing services exploited by growing startups such as Dropbox and Evernote.

"M&A specifically on cloud is going to be key, around big data, cybersecurity, software-centric deals," said Ives at FBR. "Give investors a bone, and they will believe." Lenschow, an analyst at Barclays.

Rick Sherlund, an analyst at Nomura who has urged Microsoft to put its most lucrative franchise on the iPad for some time, welcomed the idea but was more cautious on the rewards.

He estimates that an iPad Office would generate only $1 billion or so in new revenue a year, as many potential users will already have corporate licenses that can be converted to the new product.

It's unclear how much of its revenue will be surrendered to Apple, which generally takes a 30 per cent cut of app sales through its store. Microsoft and Apple declined comment.