BRIEF-Cirrus Logic set to join S&P Midcap;400 Amphastar to join S&P Smallcap 600 By: Reuters: Company News September 19, 2016 at 18:20 PM EDT * Cirrus Logic set to join S&P Midcap 400; Amphastar Pharmaceuticals to join S&P Smallcap 600 Source text for Eikon: Read More >> Related Stocks: Amphastar Pharma Cirrus Logic Inc Integral Vision Inc On Semiconductor S&P Global Inc