How Do I Determine My Gain or Loss on Stock or Mutual Funds?

If you sell shares in a mutual fund, even if you "reinvest" the proceeds in another fund, the transaction is considered the sale of stock and reportable on Form 1040, Schedule D.

The mutual fund should issue you Form 1099-B showing the gross proceeds of the shares you sold. Some companies will also include an "average cost basis" statement, which saves you the trouble of calculating the cost basis of the shares you sold.