Where does short-term risk come from? And what's the difference between HFT and LLT? If anyone knows of good high-level reading material on the subject, I'd ap

Where does short-term risk come from? And what's the difference between HFT and LLT? If anyone knows of good high-level reading material on the subject, I'd appreciate a link so I can spare you more dumb questions. I admit to having drunk some of Mark Cuban's Kool-Aid, as well as Jon Stewart's and that of some other liberal sources. Their argument, as far as I understand, is that HFT doesn't provide value proportionate with that which it extracts from a system designed to connect investors with entrepreneurs. The idea has an appealing simplicity, especially given recent history, but don't know very much about markets, so I thought I'd ask people on the other side of the debate for their take.