As mobile and digital marketing opportunities heat up, enterprise technology providers are racing to acquire some of the best and brightest marketing tech startups. Several major acquisitions have happened in the space over the past few years, helping major players build out their software suites.

Frontrunners like Salesforce, IBM, and Oracle receive the most press, but aren’t the only ones on the hunt for marketing tech startups to acquire. Read on to learn about some of the most important recent acquisitions in the space.

1. Salesforce buys ExactTarget

Enterprise CRM provider Salesforce made its biggest acquisition of the past year when it paid $2.5 billion in June for ExactTarget, a move meant to beef up its social and digital marketing offerings. The buy followed Salesforce’s purchase of social media manager Buddy Media and social analytics firm Radian6.

All of these purchases further position Salesforce as a leader among enterprise software firms building out their marketing suites. Salesforce is now able to provide clients with a suite of software that helps them manage marketing over email, social networks, and mobile devices. That Salesforce is working to provide an open platform, allowing competitors like Marketo and Oracle’s Eloqua to integrate, could, however, be seen as a weakness as much as an advantage.

2.  Oracle buys Responsys

Almost as if in direct response to competitor Salesforce’s ExactTarget buy, Oracle dished out $1.5 billion for Responsys at the end of 2013.

Like Salesforce, Oracle has made several acquisitions over the past few years to expand its marketing suite. In 2012, Oracle purchased marketing analytics provider Eloqua, as well as content marketing startup Compendium. This month, Oracle announced the merger of its marketing offerings into a single, cloud-based suite. That doesn’t mean Oracle is done buying up marketing tech firms, though.  Just this week,  Oracle announced a plan to buy cloud marketing service provider BlueKai for $400 million.

3. IBM buys Xtify

Over the past few years, IBM has been working towards building out its Enterprise Marketing Management group. The most recent acquisition of note is that of mobile messaging service Xtify for an undisclosed amount. Xtify will help IBM expand its mobile marketing capabilities. Along with Xtify, more than half a dozen products are under IBM’s EMM umbrella. Marketing solutions provider Unica, purchased in 2010, is yet another of these offerings.

The EMM group makes IBM a fierce competitor in the marketing cloud field as the tech giant now offers cross-channel marketing, marketing performance optimization, and product mix optimization. The only thing IBM has yet to do is integrate all of its purchases, which puts it a bit behind some competitors.

4. Salesfusion buys LoopFuse

Though perhaps not a direct competitor to Salesforce, Oracle, or IBM, marketing automation platform Salesfusion is still in on the marketing tech acquisition race. Last month, Salesfusion acquired marketing analytics platform LoopFuse to help expand its client roster.

Buying the marketing analytics platform placed Salesfusion right alongside other CRM providers like IBM, Oracle, and Salesforce. That overall trend points to the importance the marketing space will have for enterprise companies going forward. The move has been interpreted by some analysts as a way for Salesfusion to attract its own acquisition by one of the larger companies.

5. Unified buys Pagelever

Pagelever was perhaps one of the few marketing tech firms that didn’t get snatched up by Oracle, IBM, or Salesforce. It did get noticed by enterprise social marketing platform Unified, though, resulting in the Facebook analytics startup’s acquisition last month.

Both companies are Facebook Preferred Marketing Developers, and, while not as big as their competitors, may have an edge in the extensiveness of their offerings now that they are one. The larger enterprise competitors have a broader range of offerings, but Unified could be a better fit for companies that are looking solely for social enterprise marketing capabilities and don’t necessarily need the other features.