A penny per share tax would price small investors out of the market. If there were a penny per share tax then corporations would reverse split their shares so that a penny is nothing relative to the share price of their equity. I don't think you really want all stock to be as expensive as Berkshire Hathaway.
How many shares do you think small investors buy at a time?
If I buy 30 shares of Broadcom @ 32.00 on ETrade (their commission is $9.99), my total price goes from 969.99 to 970.29. If BRCM reverses 30:1, I save $0.29?
I'd think large companies would rather see the price stay affordable. BRK.A/B is a totally different animal.
To curb high frequency trading, a dollar per transaction would also work. For large trades, this would be neglegible, but if you're doing tens of thousands of them a day, it would add up.
