Altamont Capital Partners has acquired a majority stake in OMNIPLEX World Services, a provider of government security and background investigations services. Headquartered in Chantilly, VA, OMNIPLEX’s services include physical security support and federal background investigations for the U.S. government and commercial clients. Altamont, a Palo Alto, CA-based PE firm, invests in middle-market businesses across a range of industries, including government services, financial services, consumer/retail, industrials and healthcare.