2014 was dizzying in the number and size of industry mergers and acquisitions "as firms made aggressive moves" to acquire capabilities and market share, says management consultant FMI.

Global M&A activity was "near record" last year, adds consultant PwC, but shows signs of decline in 2015's first quarter. The firm says low oil prices, an improving U.S. dollar and rebounding European economies may drive "a modest expansion" of M&As, even as currency pricing and other factors "may obscure" deal growth.

FMI sees oil prices as a risk factor, creating a "wait and see" approach, it says in a May 6 report. Clouded public-project funding outcomes and sector mismatches in available buyers and sellers also could impact activity, says the consulting firm.