Let me tell you a secret bro. You should never trust your broker's calculated P&L.
Instead, you should ALWAYS create your own Excel spreadsheet and record the transactions/returns on your own.
Brokers design the P&L display in such a way to encourage you to trade more often, and often unnecessarily...
In fact, it's the total return that matters, as you have observed with the case on BIL ETF.
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So, for your answer, yes. Dividend is not counted as unrealized profit just for one day, i.e., the ex-date. IBKR used to deduce the correct dividend amount to be paid and deduct that figure from the daily P&L during ex-date, but in recent months I notice they purposely pretend to be a little more stupid and display unnecessarily large unrealized loses to scare investors.
Maybe just some IT issue, but always have your own records in hand to countercheck yea.
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Off-topic: I passed my qualifying exam liao. Monthly salary goes up by 500 SGD!

Wow, congrats. Soon you make the big bucks moving millions around with push of button, shaking hands with mega rich, deciding the future of us pipits and moving funds between 8888 account and shell companies.