JEDDAH — Saudi Arabia's PetroRabigh on Monday said its second-quarter net profit nearly tripled as margins on some of its products improved. The firm, a joint venture between Saudi Aramco and Japan's Sumitomo Chemical and formally called Rabigh Refining and Petrochemical Co, made a profit of SR504.9 million ($134.64 million) in the three months to June 30, it said in a bourse statement. This compares with a net profit of SR172 million in the year-earlier period. Saudi petrochemical producers benefit from subsidized oil, while product prices are closely linked to those of crude so the slump in oil prices has narrowed margins at many of the kingdom's manufacturers. But PetroRabigh seems to have bucked that trend, saying its profit surge was due to an improved spread on some products. In the first quarter, the company posted a 50 percent drop in net profit. Meanwhile, Saudi International Petrochemical Co (Sipchem) reported a 55 percent drop in second-quarter profit on Monday, missing analyst forecasts as its earnings were hit by plant closures and falling product sales prices. Sipchem made a profit of SR110.1 million ($29.4 million) in the three months to June 30, down from SR244.6 million in the prior-year period, according to a bourse filing. Analysts polled by Reuters had on average forecast Sipchem would make a quarterly profit of SR133.3 million. Sipchem blamed the profit slump on its closing of some plants for maintenance during the quarter, plus a "significant decrease in product sales prices." The company in June said it would pay a cash dividend of SR0.6 per share for the first half of 2015, in line with the payout for the corresponding period of last year. Tasnee swings to net loss Saudi Arabia's National Industrialisation Company (Tasnee) on Monday said it swung to a net loss for the second quarter, which the petrochemical producer blamed on lower product sales prices and higher costs as it missed analyst forecasts. Tasnee made a net loss of SR107.7 million ($28.7 million) in the three months to June 30, according to a bourse filing. This compares with a profit of SR408.3 million ($108.75 million) in the same period a year ago. Analysts polled by Reuters had on average forecast Tasnee would make a quarterly profit of SR96.5 million ($25.72 million). The diversified industrial firm has interests in petrochemicals, metals and chemicals and is one of the world's largest producers of titanium dioxide through its Cristal subsidiary. It cited lower product sales prices and higher general and administrative costs for the quarterly loss. Petrochemicals' prices are closely correlated to those of oil, with crude prices tumbling since mid-2014. Saudi producers enjoy subsidized feedstock costs, so lower oil prices reduce their margins and lessen their advantage over foreign rivals that do not receive such benefits. Tasnee also swung to a net loss in in the first quarter. — SG/Reuters