Thanks Steve- Yes, PM means in pre-market trading. You have pre and post market trading for those that can't get enough. These are official, regulated markets albeit not on the respective official exchange. They are run by large broker dealers on the ATS-alternative trading system.
Main facilitators being:
Interactive Brokers
Charles Schwab
Fidelity Investments
E*TRADE (Morgan Stanley)
Webull
Robinhood
NB: Not to be confused with T212 or any other platform offering 24hr trading which is completely closed market where they offer you whatever price they think you will pay/sell at. In my opinion, to be avoided as the naive will not strike a good bargain!