Large companies can gain advantages because of three reasons. First, there are economics of scale, they are simply more efficient then their smaller brethren. Second, they have market power and make extra profits based on that. Third, they lobby aka use their money and power to buy political outcomes.
I don't see how this is related to adaptability. Sure, you can claim that based on these three advantages they are not forced to adapt much or that they are such large sclerotic bureaucratic monsters but I see e.g. a lot of adaptability in investment banks. They were already well-off but have changed to become even more efficient. As a teenager I worked for some time for a very small IT company and compared to these large innovative IT companies it was incredibly static.