Wal-Mart de Mexico SAB, Latin America’s largest retailer, fell the most in a year after the stock exchange said the company’s weighting in Mexico’s benchmark index may be cut next month.
Walmex declined 4.2 percent to 34.06 pesos at the close in Mexico City trading, the biggest drop on a closing basis since Aug. 15, 2012. America Movil SAB, which also could see its weighting reduced, lost 2.8 percent. The benchmark IPC index retreated 1.3 percent.
The exchange released on Aug. 16 its preliminary estimates of the updated weightings, which are scheduled to go into effect Sept. 2. The new levels take into account revised estimates for the number of shares each issuer has trading in the open market, known as free float. Final figures will be released Aug. 29.
Many investment funds try to replicate the performance of benchmarks such as the IPC or the Standard & Poor’s 500. Changes in the underlying index can prompt managers to buy or sell stocks to match the new weightings.
Mexico City-based Walmex will probably drop to a 7.3 percent weighting on the IPC, from 9.7 percent now, according to the statement. America Movil will likely fall to 15.9 percent from 17.4 percent.
Fomento Economico Mexicano SAB, Latin America’s biggest convenience store operator, will probably see its weighting rise to 10.7 percent from 9.1 percent. Its shares rallied 3.5 percent today, the most on the IPC.
Other stocks getting a boost include lender Grupo Financiero Banorte SAB, which will probably rise to 8.1 percent from 7.1 percent. Its shares climbed 0.8 percent.
Walmex has retreated 19 percent this year.