The value of mergers and acquisitions deals around the world in 2012 was nearly half the amount made five years ago, when the financial crisis first bared its teeth, a leading accounting and consulting firm said Wednesday.

Despite big deals such as Rosneft’s takeover of fellow Russian oil company TNK-BP for a projected $54.5 billion, and Glencore International PLC’s $45.8 billion acquisition of miner Xstrata PLC, Ernst & Young is forecasting that the value of global M&A was 47 percent lower in 2012 at $2.25 trillion, against 2007′s $4.3 trillion. The company noted a shift in activity from developed economies to high-growth ones in Asia and Latin America — the value of deals in the U.S. halved while those in China doubled.