Friday-Monday Effect During $SPX Trends

There is a good correlation between up trending markets and a positive close on Fridays. Since the start of May through today, down weeks almost always end with a down Friday. The reverse is also true: up weeks end with an up Friday about 75% of the time. In the chart below you can easily see the correlation.

Another effect is also taking place: Fridays and Mondays tend to alternate direction. Thus, over this period of time (n=42 weeks):

1. When Friday is up (n=25), Monday is down 75% of the time.
2. When Friday is down (n=17), Monday is up 65% of the time.

In an uptrend, beware of down Fridays. 

Even more so, in a downtrend, look for a strong close on Friday for a possible start to a reversal.

Uptrends tend to have a positive close on Friday; down weeks tend to have a negative close on Fridays:

Monday's are the reverse:

These charts are via Cobra.