NEW YORK (CNNMoney) -- It might be easier to get a Zipcar rental on weekends now that the popular urban car-sharing service is being acquired by traditional car rental company Avis Budget Group.
The companies said Wednesday that Avis has agreed to buy Zipcar for about $500 million, or $12.25 per share in cash, which is nearly 50% above the closing price of Monday.
Zipcar's stock surged Wednesday morning to match Avis' valuation. But the stock is still about 50% below about its initial public offering price of $18.
The company made its market debut on April 14, 2011, and surged 70% that first day to a market cap of $1 billion. But then the stock price peaked and made a precipitous slide of more 50% up until Wednesday's rally.
Avis said that it plans to use its fleet of rental cars to beef up Zipcar for its weekend demand, "which is currently constrained by fleet availability."
As a "car sharing" company, Zipcar operates under a slightly different model, appealing to customers who would rather rent a car by the hour, instead of by the day, though it offers services for both. Avis and Budget offer rentals on a daily or weekly basis.
The deal requires final approval from Zipcar shareholders. Avis and Zipcar expect the deal to be completed in the spring.
Citigroup is the financial adviser for Avis. Morgan Stanley is the financial adviser to Zipcar.