After spending $4 billion on acquisitions this year, Salesforce buys yet another company

Salesforce has bought a startup called HeyWire, adding to its $4 billion acquisition spree.

In a blog post Wednesday, HeyWire CEO Meredith Flynn-Ripley announced the deal. HeyWire's software, which makes it easy for companies to deliver messages through the 1-800 line, will be integrated with Salesforce's Service Cloud business once the deal closes.

The financial details of the deal were not disclosed. HeyWire, founded in 2009, has raised a total of $13.3 million so far.

HeyWire is the latest company Salesforce bought this year. Salesforce has been buying companies at a record pace this year, spending nearly $4 billion over the past 12 months on acquisitions.

The spike in M&A has some investors concerned about the company's growth, as it failed to meet its billings forecast and revenue guidance in its most recent earnings.

But Salesforce CEO Marc Benioff doesn't seem concerned about the pace of acquisitions, saying the M&A market just opened up this year with companies becoming available at reasonable prices. During the company's earnings call, Benioff hinted it will likely continue to scoop up companies for the rest of the year.

"This M&A window, I talked about that I think on the last call, openly in the press, seems to have opened for the year. I think it will probably close, probably at the end of this calendar year. But it's been incredible time for us to acquire some phenomenal assets," he said.