They, too, could force a higher transaction value or force Archipelago to give more than the 70% the NYSE members are already getting in the new company.
It will run up transaction costs and force unwanted capital gains on you--gains that have to go on your tax return, unless you are investing through a retirement plan.
Morgan Chase was grilled on national television last year in the Senate's Enron hearings, which failed to uncover a smoking gun at the bank or force it to restate a single transaction.
Even if such paranoia were justified, slimming down this market via a transaction levy would be an application of brute force when bank funding is already fragile.
The SEC also has to decide whether to force brokerage firms to break down the prices between what clients pay for transaction services and what they pay for research.