I'm not super experienced/knowledgeable with Bitshares... BUT, from what I've gathered - if the amount of Bitshares in your wallet is going DOWN, the values of those Bitshares will simultaneously be going UP...

my experience is with OpenLedger - so I'm looking at the total BTS value figure at the top - so this value may not be the actual BTS number I've invested in, but the value of ALL my holdings as calculated in BTS price... so it'd be THIS number of BTS that changes along with the BTS price/value...

I don't know if this is a complete answer to your question, though hope it somewhat helps clarify...