Tested Binance's pre-market trading for US stocks, and it basically aligns with previous assumptions. The premiums are all taken by market makers (who are they?). Limit orders at or slightly above the current price don't get filled, which is understandable, but when placing limit orders higher than the current price, the execution price turns out to be exactly your limit price? Instead of an average execution price? A price of 254, placing at 255, and the execution price is 255? This slippage is way more than the fees.