Index funds, as a concept

An index is a list of securities and a rule for their weights. An index fund or ETF is a pooled portfolio that tries to track that list instead of picking winners. You own a slice of the pool. You do not own the index itself, and the fund can lag the index by its fee and by the practical mess of trading.

Why costs show up in a compound-interest chart

An expense ratio is a percent of assets each year. It is not a one-time commission. In the calculator, the honest way to reflect it is to lower the return you type. A 7% market illustration minus a 0.05% expense ratio is still about 7% for a sketch. The same illustration minus 1% is a different life. The chart will not warn you. You have to type the net number.

Broad stock indexes have had long periods of high returns and long periods of poor ones. A fund that tracks a broad index inherits both. Diversification across hundreds of companies removes the risk that one bankruptcy zeros you out. It does not remove the risk that the whole market falls and stays down while you are withdrawing.

Indexes are not all the same risk

A total U.S. stock market index, a short-term Treasury index, and a narrow thematic index can all be 'index funds.' The word does not tell you the risk. Read what the index holds, how concentrated the top holdings are, and whether you are doubling up the same companies in a second fund. Bonds and stocks solve different jobs. A calculator return of 7% is not a bond return, and typing 7% into a plan that is actually cash will manufacture a future you cannot spend.

Educational description only. No fund, broker, or allocation is recommended.