Something 'very rare' just happened in the S&P 500

Osman Orsal/Reuters

George Goutzioudis (front) a Greek Orthodox retrieves the wooden crucifix as he swims in the Golden Horn in Istanbul January 6, 2008.

On Monday, the S&P 500 experienced a "golden cross", or a move of the 50-day moving average above the index's 200-day moving average while both moving averages are rising.

This is generally thought of as a strong, bullish trend for the market according to the folks at Bespoke Investment Group, who highlighted the move in a note.

"For the S&P 500, though, performance has been fairly bullish," said the note. "There have only been 16 prior 'golden crosses' for the S&P in the index's history, so they're very rare."

Bespoke also broke down the returns over the following week, month, three months, and six months and after an S&P 500 golden cross. Spoiler: they're pretty good.

"While performance over the next week is hit or miss, median returns over the one-month, three-month, and six-month periods are all stronger than normal," said Bespoke.

"Notably, the index has been up over the next month, three-months, and six-months following the last six 'golden crosses' going back to 1998."

This isn't to say that higher returns are guaranteed, anything can happen and a move like this usually occurs when markets are getting stronger in a long-term cyclical manner. However, it is certainly another good sign for those with a bet the markets are moving up.

Or as Bespoke cautioned: "We definitely wouldn't go buy the index because of this one reading, but it does act as a feather in the cap for market bulls."

Bespoke Investment Group