In 2014, the stock market was up 10.0%.

In 2014, the stock market was up 13.7%.

In 2014, the stock market was up 12.6%.

In 2014, the stock market was up 4.9%.

So which was it? All of them.

Specifically, the Dow Jones (an index of 30 large, well-known stocks) was up 10.0%. The S&P 500 (the 500 largest US stocks, representing 70% of the US stock market) was up 13.7%. The entire US stock market (about 3,000 large, mid-cap and small-cap stocks) was up 12.6%. And the entire global stock market (the US is about half that) was up 4.9%.

The problem: when the media talks about the market, they really mean large, US stocks. So if you are more diversified than that, they aren’t talking to you. When large US stock soar, as they did in 2014, you wonder why you aren’t doing as well. When small or international stocks out-perform, you don’t notice.

If it’s important that your returns approximate media headlines, limit yourself to large US stocks. But to maximize returns, diversify. Over the last century, diversification paid off. Some years it can feel lousy. But if you can tune out the media, you’ll be happy in the long run with a broader mix.