Financial Readiness
Three building blocks, in plain English, with no jargon and no sales pitch.

Soldiers attend a financial readiness class led by the 24th Financial Management Support Unit. U.S. Army photo by Pfc. Elsi Delgado, DVIDS (public domain).
Investing sounds complicated, but it mostly comes down to three pieces. A stock is a sliver of ownership in a company. A bond is a loan you make in exchange for interest. A fund is a basket of many investments you buy in one move.
You do not have to pick winners. Most service members never need to buy a single stock on their own. A few broad funds can spread your money across thousands of companies at once, which is the whole point.
Stocks, bonds, and funds are pieces you combine, not rival teams. Here is what each one is, and how they fit together in a simple mix.
How they fit
Most service members never need to pick individual stocks.
Source: Investor.gov (SEC)
A stock is a sliver of ownership in a company. Buy one share and you own a tiny piece of that business, plus a proportional claim on its assets and profits. Stocks have historically delivered the largest long-term returns of the major investment types, along with the largest swings in value. As a group, large-company stocks have lost money in roughly one out of every three years. Over a short window that is rough. Over 20 or 30 years, that growth potential is the reason younger investors lean on stocks.
A bond is a loan you make for interest. When you buy one, you are lending money to the issuer, a government, agency, or company, in exchange for interest payments and a promise to repay the amount at a set date. Think of it as the reverse of the auto loan a buddy signed for at the dealership outside the gate. This time you are the lender collecting interest. Bonds tend to move up and down less than stocks, so a mix that holds both tends to be steadier than one holding stocks alone. The trade-off is lower expected long-term growth.
A fund is a basket of many investments in one purchase. It pools money from many investors and buys a wide spread of holdings, so each investor owns a small slice of everything in it. A mutual fund is the most common version, an SEC-registered company that pools money and invests it in stocks, bonds, or a mix. An ETF is a fund that trades like a stock during the day. Here is why funds matter for a junior service member: one broad fund can spread your money across hundreds or thousands of companies at once, which is hard to pull off buying single stocks one at a time. A total stock market index fund, for example, owns stock in thousands of companies. An index is just a list of companies, like the S&P 500.
You may already own all three through your TSP.
If you have ever put a dollar into the Thrift Savings Plan, you are already a fund investor. You do not have to start from scratch. You just have to know what you own.
Already in: If you have money in the TSP, you are already a fund investor. The C fund tracks the S&P 500. The L funds blend several into one age-based mix.
Your TSP building blocks
Buying one broad fund spreads your money across thousands of companies at once.
Source: Investor.gov · TSP.gov
You do not have to sort this out alone. The SEC keeps plain-language basics and a free glossary of terms at Investor.gov. Your installation Personal Financial Manager or Personal Financial Counselor is free on base and can help match these building blocks to your goals. Military OneSource offers free financial counseling too. All three are linked in Sources below.
What is the difference between stocks and bonds?
A stock makes you a part owner of a company, with higher potential growth and higher risk. A bond makes you a lender who collects interest, with steadier but usually lower returns.
Is a fund the same as a stock?
No. A single stock is one company. A fund holds many investments at once, which spreads your money around in a single purchase.
Do I own stocks and bonds in my TSP?
Yes, indirectly, through funds. The C, S, and I funds hold stocks. The G and F funds are bond-style. The L funds blend them. You own a piece of each fund rather than the individual securities.
What is an ETF?
An ETF is a fund that trades like a stock on an exchange during the day. Mutual fund shares, by contrast, are bought from and sold back to the fund itself.