Among other things I find superior such as lower fees, and trading view charts etc...of all the brokers I have been with IBKR is the only one to match my spreadsheet which calculates cost basis on total net income. Every other broker I have been on at the most will calculate based on premium received for the current trade only, and ignore all previous trades. Some do not even do that...some just show the strike price as your avg cost when you get assigned.
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