I bought shares of an index fund and after few years I converted all of them to shares of a different fund. How do I calculate the cost basis of the current shares?

[rjs]

What exactly do you mean by "converted"? Normally it would mean that what you actually did was sell all the shares of the old fund and use the money to buy shares of the new fund. The cost basis of the new fund is the amount that you paid for it. The cost basis is not affected by where the money came from. The new fund is a new investment. The shares of the old fund that you sold don't affect the basis of the new fund.

The old fund will send you a Form 1099-B for the sale of the old shares. You have to report the sale on your tax return for the year of the sale.

The new fund will keep track of your basis for you. When you eventually sell the new shares, the Form 1099-B or equivalent statement that you get from the fund will show your basis. Usually they will also show your basis on your periodic account statements, and you may be able to see the basis if you have access to your account online.

If you did something other than simply selling the old fund and buying the new fund, post the details.

[fanfare]

the current cost basis of the new shares is whatever you paid for them. That will change if dividends are reinvested.

The sticky part usually is determining the cost basis of the old fund.