They have mixed liquidity. Horribilicus's chart represents the liquidity better.
FWIW Open interest is a measure of liquidity because it shows how many contracts are in trade but I find daily volume to be more important. Also, some contracts are more or less difficult than pure liquidity would suggest.
I have marked up the chart with yellow (best) to purple (worst) to indicate those contracts that might be chosen for diversity if you were going to trade a trend orientated system. ES for example is poor because, with a daily chart, it doesn't submit easily to most trend orientated strategies (imho). Swiss franc is poor because if you already have CU the two are frequently quite strongly correlated.
But these are all just hints. In the end you have to study them and do your own homework
FWIW Open interest is a measure of liquidity because it shows how many contracts are in trade but I find daily volume to be more important. Also, some contracts are more or less difficult than pure liquidity would suggest.
I have marked up the chart with yellow (best) to purple (worst) to indicate those contracts that might be chosen for diversity if you were going to trade a trend orientated system. ES for example is poor because, with a daily chart, it doesn't submit easily to most trend orientated strategies (imho). Swiss franc is poor because if you already have CU the two are frequently quite strongly correlated.
But these are all just hints. In the end you have to study them and do your own homework
