Delta's stock rose in afternoon trading on Monday, with the airline set to be added to the Standard & Poor's 500 index this week.

After the market close on Friday, S&P announced that Delta Air Lines Inc. will replace BMC Software on the index. The move is expected to happen once an investor group including Bain Capital LLC closes on its acquisition of the software company.

That is expected to happen after the market closes Tuesday.

Stocks often get a boost when added to major indexes because investment funds that mirror the indexes must buy the recently added stocks.

Delta shares were up $1.39, or 7 percent, to $21.28. The shares have traded in a range of $8.89 to $22.05 over the past year. For the year to date, the stock is up 68 percent.