FlexGunship said:
If you don't know what you're doing... buy an index and buy it as an ETF. ETFs are a beginner's best friend. These are exchange traded funds, which are like mutual funds, but with lower management costs and no minimum cost of entry. They allow you to enter an entire market without buying a little bit of everything.
Many people who do know what they're doing, stick to index funds, either as normal open-end funds from providers such as Vanguard, Fidelity, Schwab and T. Rowe Price, or as ETFs in a brokerage account.
Individual stocks have a lot of risk. To reduce that risk, you can diversify by buying stocks of a lot of different companies. But then how do you pick the right ones? You can turn the job over to the manager(s) of an actively-managed mutual fund, and hope they do a good job.
It turns out that most actively-managed mutual funds don't do any better than the market as a whole. The ones that do better, change from year to year. It's easy to see which funds have done well in the past, but much harder to see which ones will do better in the future.
You pay a price for active management. With a "no-load" fund, and a large enough balance at a mutual-fund provider, you don't pay any fees explicitly. Nevertheless, the costs are still there. They simply reduce the price per share by an amount called the "expense ratio" (ER). All mutual funds have to publish it. For actively managed funds, the lowest ERs are about 0.3% to 0.5% per year. Some are 1% or even higher.
Index funds are mostly managed by computers, so they have lower ERs, even below 0.1%. This makes it even more difficult for actively managed funds to come out ahead in the long run.
I now have all of my retirement funds that aren't in my tax-deferred plan at work, in index funds similar to what Flex has: some in "total stock market" funds (more broadly based than the S&P 500), some in "total international stock" funds (non-US companies), and some in "total bond market" funds. I'll never do better than the overall market, but I won't do any worse, either.
I happen to have a T. Rowe Price account with some of their mutual funds, plus a couple of Vanguard ETFs in a brokerage account at TRP. I picked TRP mainly because my father used to use them for his investments, but now that I've learned more over the past few years, if I were starting over I'd go with Vanguard because their costs are lower overall, and that's what I'd recommend for someone new.