Buyout houses are attempting to build up their portfolio companies more than ever before according to research that shows private equity-owned businesses made a record number of acquisitions in 2007.

Companies owned by buyout houses made 385 acquisitions in 2007, a 13.5% rise on 2006 and more than a tenfold increase on the number completed in 2000, according to research by mid-market buyout firm PPM Capital and data provider Mergermarket.