Stock markets rewarded companies such as Johnson & Johnson and Cisco who were brave enough to make acquisitions in the months after Lehman Brothers' collapse, a study released on Monday showed.

Although firms who made purchases worth $100 million or more suffered an average 25.5 percent fall in their stock price, they outperformed the wider market by 6.3 percentage points, the Towers Perrin/Cass Business School research found.

Global mergers and acquisitions (M&A) plunged 40 percent in the first half of 2009 to $941 billion, as shrinking economies, volatile markets and scarce debt hammered corporate confidence. The World Bank forecasts the global economy will shrink 2.9 percent this year.

Companies with M&A in mind should be emboldened by our analysis: fortune favors the brave, the study's authors, led by Marco Boschetti, wrote. Fears that M&A is riskier post-Lehman seem to be misplaced.

Repeat acquirers did even better, on average outperforming the MSCI World Index by 8.1 percent.

Among them, Cisco Systems Inc, Johnson & Johnson, Abbott Laboratories , BG Group Plc , and Symantec Corp all outperformed world, regional and sector indexes.

However, other multiple acquirers such as Eli Lilly and Co , Medtronic Inc and Banco Santander SA underperformed on some or all measures.

Boschetti said some acquirers were relatively weak, so the study did not simply reflect stock outperformance by strong companies, and he said stock reactions tended to be a good predictor of longer-term value creation.

He told Reuters the study also illustrated a longer-term trend of companies becoming better at sizing up rivals in due diligence, and delivering on promised synergies.

I've been doing this work for 20-odd years, and I can tell you that the sophistication of companies going through transactions has increased exponentially, he said.

The study covered 204 deals, all 100 percent acquisitions, from Lehman's bankruptcy filing on September 15, 2008, to May 31, 2009.

(Editing by Simon Jessop)

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