[halpert]

This is notoriously playing out in the ETF space. Large institutions own vast quantities in stock in competitors and competition decreases as a result. See Rise of Institutional Investors Raises Questions of Collusion.

[danielmarkbruce]

Can you give a concrete example? This seems vague. It's certainly not notorious.

[halpert]

Notorious is the wrong word you’re right. It’s an active area of research. It’s called the “common ownership hypothesis”.