Shares of Westlake Village-based homebuilder Ryland Group soared more than $2.20 or 5 percent to more than $45 per share after the company announced a merger with rival Standard Pacific of Irvine.

Though billed as a “merger of equals,” the roughly $5.2 billion deal would give Standard Pacific shareholders the majority of shares in the combined company.

Standard Pacific, which will adopt a new name, will be the surviving company. Total enterprise value including debt is more than $8 billion and the combined company will control about 74,000 home sites.

Larry T. Nicholson, CEO of Ryland, will serve as CEO of the new company and Scott Stowell, the Standard Pacific CEO, will serve as executive chair of the new company’s board. When the deal closes in the fall, the combined company will be the nation’s fourth-largest homebuilder.

Whether the combined company would be based in Irvine or Westlake Village or a third location remains an open question. A statement said the company would operate from one headquarters in California and a second corporate center on the East Coast but no location was provided.

Standard Pacific shares also rose about 5 percent or 42 cents to $8.78 on the New York Stock Exchange after the merger was announced. Standard Pacific said that it would conduct a reverse stock split in conjunction with the merger, which is expected to be a tax-free exchange of stock.

The combined company will operate a Southern California Coastal division to handle property development in the region, according to Securities and Exchange Commission filings. Between $50 million and $70 million annually in cost savings is expected after the deal closes.