Standard & Poor’s Corp will replace BBN Corp, which is being acquired by the S&P 500’s GTE Corp, in the S&P SmallCap 600 Index with closely-watched C-Cube Microsystems Inc. The company will be added to the SmallCap 600 Communications Equipment industry group in the Technology economic sector. The change will take effect after the close of trading on Monday, June 9, 1997. C-Cube, headquartered in Milpitas, California, develops and markets integrated circuits and software used to compress digital images and video signals.