I don't think the reasons are that hard to understand. M&A opportunities outside the core business are especially hard to integrate in the software sector. Goog

I don't think the reasons are that hard to understand. M&A opportunities outside the core business are especially hard to integrate in the software sector. Google and Apple never got social right - social is a field with such extreme network effects that it tends to create natural monopolies. Buying up smaller companies in that field doesn't provide a lot of help in cracking FB's castle. OTOH, Apple and Google are outcompeting each other in mobile - no other company is currently making big inroads, not even MS, even though they see it as a critical playing field for their future. And why would one of the big tech giants buy out old-economy companies (eg. in automotive) if they believe disrupting that field with innovation is much more likely to succeed? In the end, the international financial system let's them get away with hoarding and shuffling around the billions and the companies don't see killer investment opportunities. In a low-inflation period, just stuffing the money under the pillow is probably better than burning it on failed M&A.