Los Angeles real estate investment firm Rexford Industrial Realty Inc. announced on Monday it has added to its fast-growing Valley portfolio with a nearly $9 million purchase in Van Nuys. The company acquired a six-building, 78,000-square-foot business park at 14723-14825 Oxnard St. for $8.9 million, or $114 a square foot. Co-Chief Executives Howard Schwimmer and Michael Frankel said that the company sees a long-term upside for the 3.25-acre property. The industrial park is 98 percent leased to multiple tenants. “We plan to modernize and reposition this well-located property to drive rental rates on future leasing activity,” the pair said in a statement. Earlier this month, Rexford purchased a 31,037-square-foot industrial building near Burbank Bob Hope Airport in Burbank. It also acquired a 72,000-square-foot industrial facility in Paramount. Both facilities were fully occupied at close and were acquired for a total of $8.3 million. The company went public in July, raising $224 million in its initial public offering. The company was founded by L.A. real estate mogul Richard Ziman, who serves as chairman. Rexford has interests in more than 60 properties with 7.7 million rentable square feet, in addition to managing 20 other properties with about 1.2 million rentable square feet. Shares closed down 38 cents, or 2.8 percent, to $13 on the New York Stock Exchange.