Today is the 30^th anniversary of Black Monday. CNBC will be having people on all day to share their memories.

I was a bond trader at the time. After a spectacular first few months of 1987, stocks had weakened in the few weeks prior to October, but stock traders weren’t really worried. Stocks were weaker on rising rates and a falling dollar that was leading foreign investors to sell. But the spark for that Monday came from an automated trading system that was supposed to insure portfolios went awry.

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Although that automated system is dead and gone, automated trading by algorithmic programs dominate stock trading today. Experts tell us not to worry. There are failsafe mechanisms in place. But, you still should wonder what could be.ContentMiddleAd

As mentioned earlier, there was a fairly long prelude to Black Monday, but most investors were oblivious and not concerned. We don’t have similar fundamental conditions now, but we aren’t free of worry. There is North Korea, a possible Trump trade war, a stalled Congress, and something we can’t see coming.

1987 and 2017 do share one thing complacency. Active buy and sell markets indicate a healthy amount of caution mixed in with optimism. There is little of that today. The points of remembering a day like Black Monday is not to make us fearful, just watchful.

Dwight Johnston is the chief economist of the California and Nevada Credit Union Leagues and president of Dwight Johnston Economics. He is the author of a popular commentary site and is a frequent speaker at credit union board planning sessions and industry conferences.