You, yourself, do not report the transactions within a Mutual Fund. The broker will a send any capital gains distributions on a 1099-Div. If you were to sell the Mutual Fund, then you would report the gain or loss.
A mutual fund is a regulated investment company that pools funds of investors allowing them to take advantage of a diversity of investments and professional asset management.
You own shares in the mutual fund but the fund owns capital assets, such as shares of stock, corporate bonds, government obligations, etc. One of the ways the fund makes money for you is to sell these assets at a gain.
If the mutual fund held the capital asset for more than one year, the nature of the income is capital gain, and the mutual fund passes it on to you as a capital gain distribution. Form 1099-DIV, Dividends and Distributions, distinguishes this from other types of income, such as ordinary dividends.
Consider capital gain distributions as long-term capital gains no matter how long you've owned shares in the mutual fund.
Report the amount shown in box 2a of Form 1099-DIV on line 13 of Schedule D (Form 1040), Capital Gains and Losses. If you have no requirement to use Schedule D (Form 1040), report this amount on line 13 of Form 1040, U.S. Individual Income Tax Return, and check the box, or on line 10 of Form 1040A, U.S. Individual Income Tax Return. Review the Instructions for Form 1040and the Instructions for Form 1040A for more information.
https://www.irs.gov/faqs/capital-gains-losses-and-sale-of-home/mutual-funds-costs-distributions-etc/...
