Jabil Circuit is falling off the S&P 500 list of large-cap stocks and being replaced by another company with Tampa Bay ties: Level 3 Communications Inc. Jabil, a global contract electronics manufacturer with headquarters in St. Petersburg, will be switched to the S&P MidCap 400 after the close of trading Tuesday, replacing TW Telecom, according to S&P Dow Jones Indices. The S&P 500, or Standard & Poor's 500, is a stock market index based on the market capitalizations of 500 large companies listed on the NYSE or NASDAQ.