This is difficult to estimate exactly without knowing more details about the investment fund and returns, but we can make some reasonable assumptions and calculations:
* Let's assume the fund generates an average annual return of 6% over 40 years. This is a modest but achievable return for a balanced stock/bond fund.
* At a 6% annual return, that amounts to a 0.06 annual return on the money invested.
* Let's also assume an average annual inflation rate of 3% over 40 years. So the returns need to beat inflation by at least 3% to generate real growth.
* $15,000 invested today at 6% annual return for 40 years:
1) $15,000 * (1 + 0.06)^40 = $263,174
2) Inflation adjustment (at 3% for 40 years): $263,174 * (1 - 0.03^40) = $79,378
* So after 40 years, the initial $15,000 investment could be worth around $79,378 in today's dollars.
* As a very rough estimate, if inflation averages out and the nominal returns are decent but not too high, the $15,000 could grow to $100,000 to $200,000 in 40 years. A lot will depend on how the specific fund performs versus the broader market and economy.
* The future value will also depend on whether any money is withdrawn or added over the 40 years. I have assumed the full $15,000 is invested for the entire 40 years.