After raising $22 million in May this year, UK-based social media monitoring startup Brandwatch has clearly been hunting around for arrows to add to its quiver. Its gaze has alighted on another UK startup, PeerIndex: Brandwatch has bought PeerIndex, a specialist in social influencer mapping, in what is its first acquisition. Terms of the deal were undisclosed but TechCrunch understands it was done mostly for shares in Brandwatch, with some cash. Peer Index had raised a total of £5 million. As part of the deal, founder Azeem Azhar and his 10-strong team will join Brandwatch, which employs around 300 people. Peer Index had originally started out looking like a competitor to Klout, with people able to chart their social influence among their peers. It pivoted some time ago into a B2B product aimed at marketers. PeerIndex had, in the last month or so, been in the midst of raising money on the Seedrs crowd equity platform. It pulled out of the process when the offer came in from Brandwatch. The two companies have complementary strengths: Peer Index's in content and audience mapping and Brandwatch's in analysis. Azhar will head the PeerIndex product group while also joining senior management. He will also be leading on a new “stealth product” combining the two technologies. In its time, PeerIndex had built one of the world’s largest independent Twitter author databases and released much-published lists around the most-influential Twitter users, Twitter 140 and Finance 50 among them. But ultimately the business market is demanding more complete solutions for their social media efforts, and this is where a deal like this one made sense. "The market is changing," Azhar told me. "It's all about whole-product companies, and customers buying from big enterprises. We have found every one of our customers was either using Brandwatch or using a competitor of them." Giles Palmer, Brandwatch CEO, says the move was made because Peer Index "adds the best audience analysis and with our best content analysis. That helps marketers know where to position their messages. For example, we’ll now be able to say why things have spread socially by looking at the content, the message and who shares it - and understand the virality. Because of Peer Index we’ll know who are most likely sharers of a message and how they are networked." Brandwatch has 1,200 customers and currently makes 50% of its revenues outside of the UK, largely in the U.S.