Brambles Ltd., the world’s largest supplier of pallets used to move and store goods, tumbled by a record in Sydney trading on concern it may lose contracts when Wal- Mart Stores Inc. reviews its supply agreement.

Brambles shares fell 10 percent, wiping A$1.5 billion ($1.4 billion) off the company’s market value. It’s the largest fall since the company combined its London and Sydney traded shares into a single Australian listing in November 2006. The stock price slump is an “over-reaction,” Sydney-based Brambles said.

Wal-Mart, the world’s largest retailer, may deal directly with other pallet suppliers instead of relying on Brambles, the Australian company said today, threatening contracts in its largest market. Under their existing agreement, the U.S. retailer recommends its suppliers use the distinctive blue CHEP pallets for deliveries, making them easier to sort and return.

“There’s a lot of uncertainty about what this means,” said Rob Patterson, who manages the equivalent of $3.8 billion at Argo Investments Ltd. in Adelaide, including Brambles stock. “It’s certainly not a positive development.”

Brambles dropped A$1.03 to A$9 at the 4:10 p.m. market close in Sydney, cutting its market value to A$12.6 billion. The stock has slumped 22 percent this year, outpacing the 14 percent slide on Australia’s benchmark S&P/ASX 200 Index.

Wal-Mart doesn’t deal in long-term commitments. It has difficulty seeing beyond the next billing cycle when considering alliances with suppliers and its next round of purchases. The watch phrase is not what have you done for me lately, but what will you do for me today.

What has Wal-Mart done for you today?