Persistent rumors of an acquisition have been floating around Salesforce for weeks now.

The market has twice halted trading of Salesforce’s stock in the last two weeks — once on April 29 and again on Tuesday. This was necessary because the price spiked up dangerously fast on news that the cloud company was hearing buyout offers.

News reports didn’t name a suitor, but the likely suspects soon narrowed down to Microsoft. It’s one company with the bucks to buy Salesforce (for cash, if it wanted to), and it has the most to gain from doing so.

A Microsoft deal makes sense on a number of strategic, financial, and cultural levels.

CRM is just the start

A good place to start in the discussion is with customer relationship management (CRM) software — though this doesn’t mean it’s the key driver of a potential deal.

CRM is Salesforce’s heritage (so much so that its stock ticker is CRM), and it’s still bringing in a large chunk of its revenue by selling cloud-based solution to large enterprises. Microsoft also sells such a platform, and it dominates the field of companies that sell CRM to small and medium-sized business.

“I would not be surprised to see Satya [Nadella, Microsoft CEO] make a bold move like this to remake Microsoft,” Sugar CRM CEO Larry Augustin tells VentureBeat. “Salesforce sells a suite of cloud applications to large enterprise; that’s almost the antithesis of Microsoft, which has built itself around traditional software in primarily the consumer and SMB markets.”

In the world of CRM, this would be a powerful combination.

“Combining the two would sew up the market for them and put tremendous distance between them and the second and third players — SAP and Oracle,”  former Salesforce SVP of product Chuck Ganapathi tells VentureBeat.

Cloud apps cometh

Perhaps more important is Microsoft’s need to make a strategic move toward a cloud-based future. Nadella has said that he wants to move his company toward a “mobile first, cloud first” approach to the enterprise, a strategy that Salesforce pretty much invented.

Microsoft’s core Windows, Exchange, and Office businesses are making money, but they are increasing being commoditized by pressure from low-cost options like Google Apps, which Ganapathi says is being sold to enterprises for “next to nothing.” This means that Microsoft has to look for ways to replace that revenue in the future.

“The application layer of the stack is booming and Salesforce is its darling,” Ganapathi says. “Additionally, integrating Salesforce natively with Microsoft’s productivity tools [Outlook and Office] could really cement Exchange’s position in the email world and guard against Gmail’s advancements while also improving CRM adoption,” he says.

The marketing cloud

If Microsoft does end up taking out Salesforce, we may all look back 10 years from now and see that it was really all about the marketing cloud.

“Marketing doesn’t have a core technology platform the way other departments do,” says VentureBeat Insight analyst Andrew Jones. “But a marketing cloud has the potential to become that platform. Whoever makes the biggest inroads there is going to make a lot of money, as marketing budgets continue to grow.”

Chief marketing officers (CMOs) are becoming increasingly important (and well-funded) buyers of IT, and right now Microsoft is “nowhere in that equation,” as Ganapathi puts it.

Salesforce, on the other hand, has a well-developed marketing cloud and does a good job competing for a share of CMO and chief sales officer budget. Microsoft would have to go a long way to bring its own marketing cloud to that level, so it might be a better idea to buy one rather than build it.

Microsoft can afford it

Microsoft, with its $95.4 billion in cash and short-term investments, is certainly in a financial position to buy Salesforce. Oracle could arguably buy Salesforce, helped by its $13.7 billion in cash and a further $30 billion in marketable equities that could be liquidated quickly. SAP is far less likely, having only $5 billion in cash on hand.

There’s history

The CEOs of the two companies, Salesforce’s Mark Benioff and Microsoft’s Nadella, are friends. That’s well-known. And they see the world in a similar way: Nadella, after all once ran cloud operations at Microsoft.

There’s business history, too. The two companies announced some surprising product integrations in 2014 —including Salesforce1 for Windows, Salesforce for Office, and Power BI for Office 365 and Excel integrations with Salesforce.

On March 18, Salesforce launched a new app that lets users of Outlook 2013, Office 365, Outlook for Mac, or the Outlook Web App to check out Salesforce CRM information right from within their inbox.

And a Reuters report from Wednesday claims that Nadella has actually made an offer for Salesforce once before.

Shared customers, verticals

“Microsoft and Salesforce have a huge number of mutual customers and a shared goal to enable productivity and lock those customers in to their solutions for good,” said  in a VentureBeat op-ed May 1.

Salesforce and Microsoft each do business in a wide array for markets, such as airlines, banking, and health care.

In health care, for example, Microsoft provides much of the communications and coordination software that hospitals and medical groups use. It also offers the health data platform HealthVault, which providers use to access personal patient record data and fitness tracking data.

Salesforce wants to increase its presence in health care, and is now working with well-established diagnostic instrument vendor Phillips to do so. A number of new digital health apps are now being built on the Salesforce cloud platform as well.

No marriage is perfect

Of course, Microsoft-and-Salesforce coupling would cause some messiness. The two companies already share lots of common customers, who might be confused by the mishmash of services, especially if they begin to merge (Salesforce CRM built into Microsoft email, for example).

But the marriage of the software pioneer and the cloud giant could be a powerful one, and it would surely reshape the enterprise software and service business in a big way.