We must acknowledge the turmoil in the equity markets, and do so by discussing an infamous anniversary. On the off-chance you were unaware, China’s stock markets had their shortest trading day ever on Thursday as China’s CSI 300 Index plunged 7 per cent, triggering a full-day trading halt less than 30 minutes into the session. That followed Monday’s similar losses and market closure.

The reaction overseas was swift, as Europe fell almost 3 per cent, and US stock futures followed the rout. Gold bugs finally found some relief from their five-year bear market, as the shiny yellow metal rallied to $1,100.

That all this action should occur January 7 is a wondrous coincidence. As students of market-timing history all know, on January 7, 1981, one of the world’s most-heralded market timers made one of the world’s most egregious market calls. This year is the 35th anniversary of Joseph Granville’s “sell everything” missive to clients.

The Wall Street Journal reported that the “Granville Market Letter, which thousands of investors relied on for stock-market advice” often moved markets. The result of his historic sell recommendation was a 2.4 per cent decline in the Dow Jones Industrial Average on what was, at the time, record volume.

Granville had come to fame during the 1970s, a challenging period of no net gains in markets, when shares staged huge rallies followed by brutal sell-offs. He had a run of prescient calls, and according to my colleague Josh Brown, at the peak of Granville’s popularity in 1981, he had 16,000 subscribers paying $250 to $3,000 a year for his advice.

Subsequent research by Ed Thorpe and others published in the Journal of Portfolio Management debunked the value of those signals. For those interested in learning more about Granville, there is a full chapter devoted to him in Brown’s book, Clash of the Financial Pundits: How the Media Influences Your Investment Decisions for Better or Worse.

I bring Granville for obvious reasons: The anniversary of his terrible market call coincides with the unnerving plunge in Chinese markets. For those of you who may be unfamiliar with the whole story — spoiler alert! — here is the coda to Granville’s market-timing recommendation. The year 1981 was just about the start of the greatest bull market the world has ever seen, rising 1,447 per cent during the next 20 years. Granville, who died in 2013, never managed to admit his error or reverse himself; he ended up consigned to the dustbin of history, his track record in tatters.

Mark Hulbert, who tracks the performance of investment newsletters, noted in 2005 that Granville’s letter was at the bottom of the “rankings for performance over the past 25 years — having produced average losses of more than 20 per cent per year on an annualised basis.” Ouch.

I bring up Granville as a reminder of the many risks we undertake when we a) try to time markets; 2) take ourselves too seriously; and 3) refuse to acknowledge our fallibility.

It’s the last of those three that has been most resonant this week. Some perennial bears have been declaring vindication for their great market insight — this despite having missed the better part of a 250 per cent rally since this bull market began.

My colleague Ben Carlson makes several astute observations about this, perhaps the most important being that “your favourite pundit isn’t going to be able to help you make it through the next bear market”.

A close second is that “the majority of the people who have been scaring investors by predicting a bear market every single month for the past seven years will be the last ones to put their money to work when one actually hits”.

The bottom line is this: The relentless rising trend for markets has been broken, and whether it is going to recover anytime soon is unknowable. Your best bet is to have a plan, stick to it and keep your own counsel.

Oh, and don’t to be a Granville. It’s a career-ender.

Barry Ritholtz, a Bloomberg View columnist, is the founder of Ritholtz Wealth Management. He is a consultant at and former chief executive officer for FusionIQ, a quantitative research firm.