Two panels one conduit?

[TxShocker]

I have an existing panel located on 4th floor of a remodel, we will reuse this panel and install a new panel next to it. Both panels are fed from the same panel in the basement. Existing panel has a 4" conduit to it (which is way over sized). My question is, can I put a j-box on the 4" conduit and install both panel feeds in the same conduit from the basement then run from the j-box to each panel or does both panel feeds have to have their on conduit?

 

[iwire]

Yes you can put two feeders in one conduit but don't forget to apply the derating rules.

 

[TxShocker]

That is what I thought but could not find the reference for it, thank ya Sir.