Middle-market dealmakers polled last month say deal flow increased in June, but the rate of growth slowed from May.

The mid-market M&A conditions index came in at 56, down from May’s score of 57.9. A reading above 50 indicates an expansion in M&A activity, while a reading below 50 indicates a contraction. At the start of summer, June often turns out to be a challenging month for mergers and acquisitions.

Gigamon (GIMO) is cutting its second-quarter revenue forecast. The maker of network traffic management software says it ran into challenges closing deals during the period. Gigamon now expects revenue of $34.5 million to $35 million, compared with its previous outlook of $38 million to $42 million.

And Silicon Image (SIMG) expects to report second-quarter revenue between $58.5 million and $60.5 million, down from $71 million to $76 million. The chip maker blames lower-than-anticipated mobile chip shipments to a significant customer and a delay in royalty revenue.

Adam Shapiro joined FOX Business Network (FBN) in September 2007 as a New York based reporter.