[youeseh]

Two types of limiting happened:

Some brokerages put a complete stop on trading the share - no buying or selling. Fair enough.

Others (this includes Robinhood, which I believe had the largest number of GME shareholders) stopped allowing purchases but continued to allow selling. One of their excuses is that they didn't want to take people's ability to exit their positions. This of course, played into the hands of anyone trying to cover their short, as it artificially increased the number of sellers compared to buyers.

Finally, Robinhood allegedly closed out positions of people who'd purchased GME "on margin" - the thing is, if you sell a share in company A, and buy a share in company B on the same day, you might be buying shares in company B on margin, because it takes two days to settle company A's share sale. So, even though you may think you bought shares of company B fair and square, RH could still have closed your margin position.