Acacia Communications said it raised $20 million in a round led by Summit Partners and joined by existing investors Matrix Partners , Commonwealth Capital Ventures and Egan Managed Capital. Summit Partners Managing Director Peter Chung will join the company’s board.

Heart to Heart Hospice, a 10-year-old, Plano, Texas-based hospice care company, has received a minority investment from Boston-based Summit Partners, the growth equity firm. Terms of the deal aren’t being disclosed.

This week peHUB is highlighting a handful of positions based in Boston, San Diego, New York and London.

Social software startups providing products to businesses have been catching the eye of venture capitalists for some time. Thirty-eight of 55 companies identified by Jeremiah Owyang, a partner at the research firm Altimeter Group, received funding.

Payment Alliance International is up for sale and expected to draw bids from middle market private equity firms, three sources say. Bank of America Merrill Lynch is advising on the auction

Fortegra Financial Corp., which is backed by Summit Partners, has acquired a majority stake in Digital Leash, which does business as ProtectCell. The deal closed Dec. 31. Financial terms were not announced. Novi, Mich.-based ProtectCell provides wireless device protection plans and mobile services sold to consumers. News of the deal was announced by Quarton Partners, which advised ProtectCell.

Lazada, the online retailer for Southeast Asia, received €20 million in its German holding company from growth equity investor Summit Partners. The company will use funds to further its growth.

Brazilian fashion online retailer Dafiti has secured a fourth round of investment worth $65 million. The new round is led by New York-based Quadrant Capital Advisors, which committed $32 million. Additional funding will come from AB Kinnevik, Summit Partners and other investors through a German holding company.

FleetCor Technologies has completed its previously announced purchase of approximately 3.85 million shares of FleetCor common stock at $51.91 per share pursuant to a share repurchase agreement with certain of its private equity shareholders associated with Summit Partners and Bain Capital. The share repurchase was effected in a private transaction and FleetCor funded the $200 million aggregate purchase price with borrowings under its credit facilities.

In a surprise, the U.S. M&A market seems quite steady. There were 101 U.S. announced deals this week (Nov. 25 to Nov. 30), valued at $32.9 billion, according to data from Thomson Reuters. This compares to last year, when there were 82 U.S. announced mergers from Nov. 20 to Nov. 26 (the last full week of November), totaling about $24.5 billion.