"Our finding is that most large-scale M&As do not meet many of their objectives," it said, while adding that some deals have in fact done very badly.

"It could be due to inability to preserve the distinctiveness of the target, little incentive for target management to stay, especially if a fairly large portion of the consideration value is paid upfront, and hacking away too much of the muscle of the target firm, instead of the fat," it added.

JP Morgan said that historically, the market has been initially sceptical of larger mergers of listed entities, especially the deals involving merger of a larger company into that of a comparatively smaller size.

"We find that it can be 12-18 months after a merger announcement that tangible value emerges (if it happens) for the investor, as the acquirer sets about tackling the initial burden-of-proof," it added.

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