Salesforce.com has entered a definitive agreement to acquire ExactTarget, a provider of cloud-based social media marketing solutions. Under the terms of the deal, the CRM giant will pay $33.75 per share for the Indianapolis-based firm, a 52 percent premium over its stock’s Monday closing price of $22.10.

The all-cash transaction is valued at approximately $2.5 billion, representing Salesforce’s biggest acquisition to date. Chief and CEO Marc Benioff justified his company’s massive investment in a brief statement that read: “the addition of ExactTarget makes Salesforce the starting place for every company and puts Salesforce.com in the pole position to capture this opportunity.” Scott Dorsey, Benioff’s counterpart at ExactTarget, added that “Salesforce.com’s tremendous strength in social marketing, along with its leadership position in sales and service, not only will accelerate this vision, but also provide our customers with a powerful, integrated CRM platform to transform their end-to-end customer experience.”

ExactTarget boasts that its software-as-a-service platform is used by over 6,000 brands worldwide, including household names such as Coca-Cola, Nike, and The Gap. As we learned this week, the firm’s massive stake in the social media market made it a highly attractive acquisition target for Benioff and his peers, but its ability to gain share didn’t impress Wall Street nearly as much. Investors were more concerned about the $21 million net loss ExactTarget reported in fiscal year 2012, judging by the fact that Salesforce’s stock declined by as much as five percent in early trading Tuesday morning.

The ExactTarget buyout is one of two multi-billion dollar cloud acquisitions that were announced Tuesday morning. The other is IBM’s two billion dollar takeover of SoftLayer, a cloud computing infrastructure provider that maintains 13 data centers across the US, Holland and Singapore.