Option sold in Jan 2024 acquired in Dec 2023, should this be reported as acquired 12/31/2023 marked to market value?

[wdwesley2]

... or is this handled as two separate transactions, reporting the full gain from acquisition to sale, offset by the 2023 year-end gain marked to market (which was taxed in 2023)?

[Mike9241]

I assume its a stock option. mark-to-market would only apply if you were a trader who properly made the IRC 475(f) election marking to market. Otherwise, it is treated no differently than purchasing a stock 12/23 and selling it in 1/24. the proper cost and selling price should be on your 1099-B. if you used a foreign broker that does not issue the form you use cost + expense of purchase  and selling price net of selling expenses. the must be converted to US $$$ if in foreign currenct.