Westlake Village home builder Ryland Group Inc. announced Thursday that it has completed its planned merger with Irvine-based home builder Standard Pacific Corp. The combined company, which becomes the country’s fourth-largest residential home developer, is named CalAtlantic Group Inc. Its shares will trade on the New York Stock Exchange under ticker symbol CAA. The two companies had a $5.4 billion market capitalization as of June 30 and an enterprise value of $8.4 billion. CalAtlantic will own or control about 76,000 home sites and will operate in 41 markets across 17 states. “Today our industry reaches a significant milestone as two of its best operators combine forces in the belief that our combined future is brighter. With similar cultures and long histories of designing and building quality homes and providing exceptional customer service, Standard Pacific and Ryland are each proud of where we’ve been and are confident in our future together as CalAtlantic Homes,” former Ryland Chief Executive Larry T. Nicholson said in a prepared statement. He is taking over as president and chief executive of CalAtlantic. The new company anticipates that it will achieve cost savings between $50 and $70 million by late 2016, based on purchasing, production and other synergies from the merger. CalAtlantic will be headquartered in Irvine with plans to establish an office in Northern Virginia to handle East Coast operations.