I've had a similar idea. The basic premise is that each company's stock trades once a day, at most, in a Dutch auction. On the sell side, you inform the market

I've had a similar idea. The basic premise is that each company's stock trades once a day, at most, in a Dutch auction. On the sell side, you inform the market that you'll be placing stock in a company on sale, and it sells at a known time, before which you can withdraw intent to sell. On the buy side, you can place and withdraw bids at any time, and when the auction starts, those bids are part of the auction. This works as a price signal to draw sellers in, or convince them to withdraw. The price paid for all the stock is pooled, and each seller gets a share proportional to what they sold. This would eliminate HFT (good), and should allow for price discovery and other useful market forces to do their work. It would chill out the market and dispose of the heady cocaine-fueled paper-chasing casino aspect of it. The market would converge on a daily agreement about the stock price of that company, without all the random walks and HFT coin shaving, which is not economically productive behavior.