Standard & Poor's will add Warren Buffett's Berkshire Hathaway Inc. to its S&P 100 and S&P 500 indexes after Berkshire acquires Burlington Northern Santa Fe.

S&P announced the stock index changes Tuesday. Buffett's company will replace BNSF in both indexes after shareholders approve Berkshire's acquisition of the railroad company next month.

Berkshire shareholders agreed to split the company's Class B stock 50-for-1 last week, and that move gave Buffett's company enough liquidity to meet S&P's criteria.

Standard & Poor's spokesman David Guarino says Berkshire, based in Omaha, Neb., is a good fit in the indexes because the company represents the U.S. economy and stock market well.

Berkshire shares jumped 7.5 percent to $73.08 in after-hours trading.