bingo...
i traded SPY and DIA before I ever traded YM
it was also testing my setups on DIA vs. SPY that led me to the conclusion that dow was superior for my setups
note also that DIA and YM have the same spread
technically speaking SPY has a superior spread to ES, since it trades in smaller increments. thus, it is not (especially for scalping) as close a match as DIA vs. YM
in extreme news events, the YM will have wider spikes than DIA (usually) but this is extremely short lived (fractions of a second or sometimes a little longer) since arbs will have to bring it in line
what i would do (and what i did) is trade the DIA in 100 lot blocks and treat each block like 1 YM contract for the purpose of scaling etc.
this will give you 1/5 the size of your eventual YM trades, with the same movements to play off of
also note that DIA has inferior fills to YM. so, if your strategy works on DIA, it will work on YM
i traded SPY and DIA before I ever traded YM
it was also testing my setups on DIA vs. SPY that led me to the conclusion that dow was superior for my setups
note also that DIA and YM have the same spread
technically speaking SPY has a superior spread to ES, since it trades in smaller increments. thus, it is not (especially for scalping) as close a match as DIA vs. YM
in extreme news events, the YM will have wider spikes than DIA (usually) but this is extremely short lived (fractions of a second or sometimes a little longer) since arbs will have to bring it in line
what i would do (and what i did) is trade the DIA in 100 lot blocks and treat each block like 1 YM contract for the purpose of scaling etc.
this will give you 1/5 the size of your eventual YM trades, with the same movements to play off of
also note that DIA has inferior fills to YM. so, if your strategy works on DIA, it will work on YM