beginner pm/bullion questions

[Avid_Consumer]

why are the price history of comex pit and composite symbols significantly different?

for example, platinum via tradestation, @PL.P peaked in March 1980 at 1264.25. @PL.C peaked at 1045.00

My general understanding is that the pit symbols reflect only pit executions, and the composite reflects both pit and after hours trading via the ACCESS system. i'm missing something

the same disparity exists for gold as well though by a far greater margin. the charts are vastly different and i imagine the reason is a real head-slapper when i finally track it down

 

[Avid_Consumer]

here are graphical examples

 

[Avid_Consumer]

gold

 

[SethArb]

for one thing nymex access did not exist in the 1980's ... people did do EFP's though in the spot market

 

[Avid_Consumer]

interesting, so the composite data going that far back contains some concatenation of data from different systems

there's some sort of obvious adjustment i'm missing, the price difference has pit and composite markets trading in entirely different ranges at the same time