Thanks for the explanations - it still leaves me unsettled that I have no way to check that the balance in my account matches the contributions that Delta gives to Fidelity. Month to month comparisons are clouded by the compounding investment returns (that I can’t reconcile either, because it’s an unpublished phantom investment). I don’t see why this can’t be clearer on a monthly statement - I thought the plan was commingled funds, but still an “individual” account.

As a data point, I added the flight pay earnings for the 10/15+10/31 checks. My MBCBP balance is $4 less than 16% of flight pay. Am I adding wrong?