What Are the Best Practices for Accounting Acquired Portfolio Companies via Share Swaps in Your Track Record?

Compare the price per share between your purchase price and the current price when acquired, and then record this differential as a markup. This assumes that you will have the same number of shares. If the share counts differ, then just calculate the value of the ownership position before and after using the price that you paid as the value at the start. Technically, since it is an all stock acquisition, you have not exited, so I would not characterize this as an exit.