Have you heard that a low-profile group of shareholders has significantly increased its stake in Wal-Mart and could soon own 50% of the world’s largest company? No, it’s not some secretive hedge fund looking to take over the giant retailer. It’s the Walton family.

The heirs of Sam Walton haven’t actually been snapping up shares; their family company, Walton Enterprises, just hasn’t been selling at a time when Wal-Mart (WMT) has been buying back massive amounts of stock. As the chart shows, Wal-Mart has bought back nearly 1 billion shares over the past 10 years, spending more than $50 billion to reduce its float by almost 22%, to some 3.5 billion shares.

During the same period, the Walton family, which holds three seats on the board, has kept its ownership in the retailer steady at almost 1.7 billion shares, a position worth $93 billion in late May. Consequently the Waltons’ stake in Wal-Mart has leaped from 38% to more than 48%. If the trend continues, by year-end the family would own almost exactly 50% of the company.

Neither Wal-Mart nor a family spokesperson would comment on what the corporate-governance fallout might be from the Waltons’ increased ownership stake. But it seems that the company, as a buyer of the stock, and the family, as holders, believe that Wal-Mart shares are cheap. You wonder whether the folks who brought you “everyday low prices” are onto something.