Quote from bobby000666:
"2. It is a violation of U.S. option exchange rules for a customer effectively to act as a market maker by holding itself out as willing to buy and sell securities on a regular or continuous basis. In determining whether a customer effectively is operating as a market maker, the exchanges will consider, among other things, the simultaneous or near-simultaneous entry of limit orders to buy and sell the same security; the multiple acquisition and liquidation of positions in the security during the same day; and the entry of multiple limit orders at different prices in the same security. "
IB is also a market-making firm ie Timber Hill, therefore you'd be competing against them with priority on exection since you're a customer.