The Surprising Success of Friday the 13th in the Stock Market

It's a day that's often associated with bad luck, but for the stock market, Friday the 13th seems to be quite the opposite. Recent data analyzed by the experts at Bespoke Investment Group reveals that the S&P 500 index tends to perform exceptionally well on both Fridays and the 13th day of the month. However, when these two coincide, on a Friday the 13th, the average gains for the S&P 500 skyrocket to four times the historical average daily move.

Since the adoption of the modern five-day trading week in 1953, Friday the 13th has proven to be surprisingly profitable. On these specific dates, the S&P 500 has seen an average daily gain of 3.4 basis points. Yet, Fridays alone exhibit even stronger performance, with an average daily gain of 6.1 bps and positive returns 55.9% of the time. Similarly, the 13th day of the month displays above-average performance with an average gain of 5.2 bps and positive returns 53.6% of the time.

Remarkably, the average gain for Friday the 13th climbs to an impressive 14.5 basis points, with gains recorded in 58% of instances. This substantial increase is more than four times the average daily gain since the launch of the index in 1957. It's worth noting that historical data is used to reconstruct S&P 500 performance before its formal creation.

Nevertheless, it's crucial to acknowledge that performance on Friday the 13th has varied across different months. In particular, when this fortuitous date falls in October, average performance tends to be notably weaker compared to other months. October Friday the 13ths have a median daily gain of 9 bps, placing them in the middle of the pack among the 12 months. The standout performers are the summer months of June, July, and August, boasting median gains of 49 bps, 30 bps, and 21 bps, respectively.

On the latest Friday the 13th, U.S. stocks experienced a positive start, with the S&P 500 SPX, Nasdaq Composite COMP, and Dow Jones Industrial Average DJIA all showing gains. This upward momentum was propelled by a flurry of earnings reports from major banks and financial institutions, signaling the beginning of the third-quarter earnings season.