Suppose I am making markets in SPY. I need to know where everything else is trading so that I can price it. If my prices are stale by a millisecond then I get f

Suppose I am making markets in SPY. I need to know where everything else is trading so that I can price it. If my prices are stale by a millisecond then I get filled on my SPY market making orders, but can't get my hedge in the other products because the market has moved against me.