The CRO deals just keep coming. Four have been announced since the beginning of the year,  targeting contract research organizations (CROs). The latest announcement came from Charles River Laboratories International (NYSE: CRL), which is paying $800 million for Mattawan, Michigan-based MPI Research. This is the highest disclosed price for an acquisition by Charles River since 2011.

MPI is a premier non-clinical contract research organization (CRO) that provides comprehensive testing services to biopharmaceutical and medical device companies worldwide. Its acquisition enhances Charles River’s ability to partner with clients across the drug discovery and development continuum.

This marks the company’s second deal announcement in 2018, following January’s $20 million deal for UK-based CRO KWS BioTest. KWS specializes in in vitro and in vivo discovery testing services for immuno-oncology and inflammatory and infectious disease.

Harvard Bioscience, Inc. (NASDAQ: HBIO) acquired privately held Data Sciences International for $20 million in January, and Regatta Medical Holdings, a portfolio company of GTCR, acquired Resonetics, Inc. from Sverica Capital in February for an undislosed price.

CRO deals hit a peak in 2017, with 43 acquisitions and a combined total of $21.2 billion. In 2016, 31 such deals were announced, with a combined total of $142.7 million (only three deals disclosed prices that year).

Private equity firms were particularly active in CRO acquisitions in 2017. The two largest deals by disclosed price were Hellman & Friedman‘s acquisition of Pharmaceutical Product Development, LLC for $9.0 billion. The firm had been a minority stakeholder to The Carlyle Group (NASDAQ: CG), but bought out most of Carlyle’s stake in April 2017.

Pamplona Capital Management announced the second largest deal, paying $5.0 billion for Parexel International Corp. (NASDAQ: PRXL) in June.