The HFT can't just know that you're going to place a market order, and then jump in front of all of the other limit orders that you're going to match with, with

The HFT can't just know that you're going to place a market order, and then jump in front of all of the other limit orders that you're going to match with, without offering a better price than the other limit orders. The only way that could work is if the lowest price you can buy on exchange A is $100, and the HFT knows that you're about to submit a market order, so he buys up the $100 orders until the best price is $101, and then he lists what he bought for sale at $100.99, which your market order matches against. OK, in theory this works. To avoid this, you can just submit a limit order at $100 instead of a market order. You should always use limit orders for exactly this reason, anyway: even in the absence of foul play, the order you're trying to match against might get matched by someone else in the mean time and you could get a worse price than you expect.