What Lucky Numbers Cost Investors

First, an honest label

A disclosure up front: the two studies here are about lucky and unlucky numbers, not zodiac animals. We include them because number lore and zodiac lore are branches of the same family — traditional beliefs that attach fortune to dates, signs and digits — and because they answer, with unusual precision, the question this series keeps asking. Do such beliefs have real, measurable effects on the world? They do: through human behavior, never through any power in the numbers themselves.

The relevant tradition: in Chinese-speaking markets the number 8, which sounds like the word for prosperity, is auspicious, while 4, which sounds like the word for death, is avoided. Two teams of financial economists asked what that preference costs when real money is on the table.

Traders who favor 8 over 4 — and pay for it

Bhattacharya, Kuo, Lin and Zhao gave their 2018 Management Science paper a blunt title: “Do Superstitious Traders Lose Money?” Working with limit-order data from the Taiwan Futures Exchange, they found that individual investors submit disproportionately more limit orders at prices ending in 8 than at prices ending in 4. Institutional investors show no such tilt.

The habit is not harmless decoration. The authors built a “superstition index” for each trader, and it predicted losses — mainly through bad market timing and stale orders. There is one hopeful note: the bias declines with experience. Markets are expensive teachers, but they do teach.

IPOs with lucky ticker numbers

Hirshleifer, Jian and Zhang, also writing in Management Science in 2018, turned to China’s IPO market, where newly listed firms carry numerical listing codes. Lucky codes turn up more often than chance would predict, and investors reward them: firms with lucky listing codes initially trade at a premium.

Then reality reasserts itself. Lucky-code firms underperform after listing — a relative underperformance of around 10.8% per year over three years compared with unlucky-code firms — and the lucky premium dissipates within three years.

The mechanism

Both studies trace the same chain that runs through this whole series: belief shapes behavior, and behavior moves measurable outcomes. Retail traders cluster their orders on 8s; IPO buyers bid up auspicious codes; prices, timing and returns quietly record the bill. The numbers do nothing. The people who believe in them do everything.

What this does not mean

Neither study found that 8 attracts wealth or that 4 repels it. The findings point the other way: acting as if digits had power is precisely what cost investors money, and experience eroded the habit. It also does not mean believers are foolish — the premium on lucky codes existed because enough buyers shared the intuition to move prices.

So enjoy lucky numbers the way this site presents them: as heritage and play. Your sign’s traditional lucky numbers are collected in our lucky numbers guide — worth consulting for a licence plate or a bit of fun, and, as two Management Science papers now attest, never for a trade.