Warren Buffett’s Berkshire Hathaway Inc. (NYSE: BRK.B) will enter the roster of securities comprising the S&P 500 and the S&P 100 indexes following its acquisition of Burlington Northern Santa Fe Corp. (NYSE: BNI)

The company will have roughly a 1.1 percent weighting in the S&P 500, which is “simply the proportion its float market cap is of the total index market cap,” David Blitzer, managing director of S&P indexes, said.

Berkshire is one of the largest publicly traded U.S. companies, but it was never included in the S&P 500 before because its shares were not liquid enough, something that has changed with the new 50/1 share split.

The value of the company’s shares rose significantly following the announcement due to increased demand. Typically, when a company is announced for addition to an index, investors rush to buy those securities ahead of expected institution index buying.

Berkshire is a financial sector name, Burlington is an industrial one. But according to Blitzer, the addition of Berkshire to the S&P 500 should not change the nature of the index. On the contrary, the company—post share split—“clearly fits the description” of a nS&P 500 company: “a leading company in leading industries.”

S&P has not announced the date when the change will take effect. Berkshire’s acquisition of Burlington is still pending final approvals, but the deal is expected to close next month.