M&A vs Organic Growth

Mergers & Acquisitions(M&A) has become a preferred vehicle to grow and expand in both related and unrelated areas. Cost reduction, economies of scale, acquiring competence, fewer competition, faster growth are some of the benefits of taking M&A route rather than organic growth.
But I was surprised to come to know that on average an M&A fail.

Mckinsey Qrtrly mentions that 40% of mergers fail to capture the identified cost synergies.

This is indeed very surprising. Some say that M&A only happens to increase the pay of top executives whose pay depends on size of the company. Others say that the failure to manage the change and cultural-fit is the main reason.

But it would be wrong to conclude that M&A are bad and one should go for only organic growth (There are many successful companies who have grown organically). The real challenge is to make M&A work and manage the associated change.