A 10,000-point rise for the Dow Jones Industrial Average isn’t what it used to be.

Just ask Richard Flasck. The former stockbroker at Merrill Lynch gets new vanity license plates in Ohio every time the index doubles.

He got his first Dow plate, “DJ 5000,” in 1990, when the index traded at about 2500. He upgraded to “DJ 9000” in 1995 when it hit 5000 and he wasn’t able to get the plate for 10000. “DJ 20000” followed, and when the index finally cleared that mark in January 2017, he secured “DJ 40000.”

Even though the Dow is now closing in on 30000, Mr. Flasck isn’t contemplating another change, at least not yet. The Toledo resident is sticking to the theme of the Dow doubling.

If and when the index hits 40000, the 78-year-old plans to go for a plate tied to the index hitting 80000—a plate change he predicts could happen shortly after he turns 80.