It’s time to ditch the Dow. After 120 years, the venerable Dow Jones Industrial Average is an embarrassing anachronism, abandoned by professionals and beloved only by a media that mostly knows no better. It needs to be updated or, better, replaced.

The Dow was invented by a founder of this newspaper. My direct boss and his direct boss both sit on the committee that decides on the 30 companies which make up the average. And TV news has long since picked the Dow as its gauge of Wall Street activity.

But a columnist’s job isn’t to flatter. It is to present facts. And the fact is that the Dow is deeply flawed. It is not a good measure of the broad market—indeed it is not even designed to be. It is not a good guide to investing. It is not calculated in a sensible way. And it isn’t even right.

Start with the last point. Correct for mistakes dating from the days of paper and slide rule, and the Dow in fact passed 30000 for the first time last month, according to Birinyi Associates calculations.

The biggest mistake came from the simplistic recalculation of the average when it was expanded from 12 to 20 stocks. The official Dow record shows a drop of 24%—its worst-ever day—when the market reopened in 1914 after a four-month break because of the start of World War I. In fact, the market and the Dow rose that day, but the record was recalculated without any adjustment when the measure expanded from 12 to 20 stocks two years later. Because some of the new stocks added had lower prices, the new version of the average was pulled down. So, no, there really isn’t any reason to get worked up about the average passing 20000.