If you’re buying stocks because a bullish “golden cross” chart pattern appeared in the S&P 500 on Monday, it could take months to pay off.

And history suggests that the longer you wait, the more you stand to make.

A so-called golden cross is formed when the 50-day simple moving average, which many use to follow the short-term trend, crosses above the widely watched 200-day moving average, which is seen as tracking the long-term trend. Many chart watchers believe this pattern implies that a shorter-term rebound has transitioned into a longer-term trend.

The S&P 500’s SPX, -1.11% 50-day moving average rose to 2,017.85 on Monday, from 2,012.68 on Friday, while the 200-day moving average inched up to 2,014.85 from 2,014.67. The last time a “golden cross” appeared was Dec. 21, 2015.

FactSet

There is reason to be skeptical of the pattern’s bullish message in the short term, but the longer an investor is willing to wait the more powerful that message becomes.

The S&P 500 has produced 23 “golden cross” patterns since the beginning of 1970, according to the WSJ Market Data Group.

The following are some of the performance statistics of previous “golden cross” patterns:

S&P 500 performance after appearance of ‘golden cross’ pattern Months after ‘golden cross’ pattern Average gain Number of times S&P 500 was up (out of 23 since 1970) 1 1.31% 13 3 4.61% 17 6 7.55% 19 12 11.28% 19 WSJ Market Data Group

On a side note, the S&P 500 was up three months after the appearance of the last nine “gold crosses.”