[dasudasu]

Non-insider trading is liquidity. That’s why people pay for retail trading volume (payment for order flow). Not because of nefarious reasons. Just because it represents liquidity. With no liquidity it’s impossible to enter or exit trades efficiently.

[jfengel]

Though at this point volume is far higher than needed for liquidity. We do not need companies holding stocks for a millisecond in order to squeeze out arbitrage, and we do not need day traders hoping to arbitrage noise.

The stock market would not be noticeably less liquid if people had to hold stocks for 24 hours, but volume would drop like a rock.