ABSOLUTELY COMPELLING ECONOMICS, page-270

A perception that institutions with larger blocks will be better at calculating and then extracting perceived value in a takeover. Also that they will have stickier hands with more illiquid positions providing a better price floor. Obviously you can hypothesis scenarios where this would not be the case and where a register of single minded retailers was stickier but on balance it seems a reasonable inference that (ordinarily) an insto heavy book is going to fare better in terms of extracting shareholder value during a takeover.