When the market starts down 8 percent, it usually comes back

The S&P 500 is down about 8 percent to start the year. That's an infrequent situation — in fact, this is the first time we've been so far down this early in the year in three decades, but it doesn't mean the market is doomed.

The market often bounces back when it's this far down in the first quarter. Hover on the chart below to see the odds change during the course of the year. Notice it keeps going down, which makes sense. The longer the market stays negative during the course of the year, the harder it is to end up finishing positive.

The chart is a bit wild because there haven't been a lot of instances with an 8 percent drop to start the year. For days that have only one or two sample years that are this bad, the calculated probability jumps is either zero, 50 or 100 percent.

About half the time a year started off this bad, it ended up bouncing back to positive territory by the end of the year. The curve smooths out later in the year, when a year-to-date return of negative 8 percent ends with a gain about 30-40 percent of the time.

All hope isn't lost until late into the third quarter of the year. The market has never recovered from an 8 percent drop that late. The first and second quarters, though, aren't so much of a hurdle to overcome.

S&P 500 historical data since 1978 was used to build a probability curve for each weekday of the year.