US stocks decline at the open as we head into a super-soft seasonal period

<p>The mood in markets has flipped in the past hour and the S&amp;P 500 is down 19 point at the open. It was trading higher up until 8:30 am ET.</p><p>It's quad witching today which means it's the expiring of monthly:</p><ul><li>stock index futures, </li><li>stock index options, </li><li>stock options </li><li>and single stock futures</li></ul><p>I tend to think the importance of it matters less with so much trading in weekly and daily options now but the lore continues. Perhaps more importantly, <a href="https://twitter.com/donnelly_brent/status/1702470879244906971" target="_blank" rel="nofollow">Brent Donnelly points out</a> that Sept 16-Oct 9 is the worst season period of the year. I think some of that is a skew due to the Lehman year but it holds up nonetheless. </p>

This article was written by Adam Button at www.forexlive.com.