I held ISO shares of a company that was acquired in 2021, and all my shares were purchased during the merger. In 2022, I received an 1099-B for this sale and filed it. The cost basis was left blank (unknown to the broker), so I computed it following the instructions on TurboTax. Later in the year, I received a notice about a cost adjustment of the sale that got me extra earnings. Let's say I bought the shares at $5/share and they were purchased at $10/share. After cost adjustment I got an extra $1/share. Now, in 2023, I received a new 1099-B with the extra $1/share. The cost basis was again left blank. How should I file this 1099-B? It doesn't make sense to report the same cost basis because that would appear I had capital loss ($5/share -> $1/share), which I didn't have. But leaving it blank/0 also doesn't make sense because I'm just getting the earnings in two separate transactions. Any help is appreciated. Thanks!
