You can make pricing rules for the market makers, but not
the independents.
Someone may want to accumulate a stock over time. He can put in a variety of bids, different prices, active different amounts of times. Would you tell him he can't bid this way?
Someone shows up in the market, needs cash fast, and offers more shares than the market maker can absorb. Must he price it higher due to the rule, and then get no buyers? Brokers have hundreds or thousands of clients that must take these orders and then send them up to the exchange, constantly.
If you make it a law, it will only happen in the US, and then the trades will happen out of the US. Will you put capital flow controls in place to avoid this? Then the stocks themselves will move, and the US will simply be out of the game.
