Hello, I would like to know that, if Im buying in emini and theres no liquidity it could affect price isnt it?. But how is that possible, if price on emini is determined by the underlaying movement of corps in sp500? Example, Ibex35 depends on the corps like BBVA, Santander.....
It's the same market. Think of the emini bids and asks and the collective bids and asks for the stocks in the S&P 500 as being a single market, a single entity. If they get decoupled, it's like a crossed market (bid > ask), and somebody fast is going to do the abitrage and take the risk-free money.
I used to trade YM off the Dow chart, as the DOW chart was always slightly ahead, well at times, like 5 seconds.