MPM Capital, a large venture firm with offices in Boston, San Francisco and New York, said it has raised a new $550 million fund, to focus mostly on biotech and specialty pharma companies, but with 15 percent earmarked for other medical companies.

The fund is much smaller than its previous $900 million fund, in part because of the departure of many of its partners two years ago to form Clarus Ventures. However, you will not see any of that talked about in its press release today, which is here.