Insurer American International Group Inc reported a 5.6 percent jump in quarterly operating profit, driven by investments in one of China’s biggest insurers and earnings from aircraft leasing company AerCap.

AIG, the largest commercial insurer in the United States and Canada, also boosted its share buyback program by up to $5 billion and more than doubled its quarterly dividend to 28 cents per share.

Operating income after tax increased to $1.9 billion, or $1.39 per diluted share, in the second quarter ended June from $1.8 billion, or $1.23 per diluted shared, a year earlier.

The operating income was bumped up by a more than doubling in pretax earnings to $127 million from AerCap Holdings NV , the world’s largest independent aircraft lessor.

AIG, which is trying to exit AerCap, sold most of its 46 percent stake in early June.

The insurer, which traces its roots to a two-room office in Shanghai in 1919, also gained $170 million from investments in the People’s Insurance Group of China Ltd and its subsidiary, PICC Property and Casualty Co Ltd.

However, AIG’s underwriting operations continued to struggle with plummeting commercial property and casualty insurance rates.

Pretax operating profit fell 4 percent to $1.19 billion at the commercial property and casualty insurance business, traditionally AIG’s forte. The company also paid out $88 million more in catastrophe losses.

Industry rates for commercial property and casualty insurance fell for the third straight time during the second quarter, according to a recent survey by the Council of Insurance Agents & Brokers.

AIG’s property and casualty unit’s combined ratio, the percentage of premium revenue paid out in claims, inched up during the quarter to 98.8 percent from 96.5 percent.

A ratio below 100 percent means an insurer earns more in premiums than it pays out in claims.

Earnings from mortgage, institutional markets, life and personal insurance also declined during the quarter.

Net income attributable to AIG fell 42 percent to $1.8 billion, or $1.32 per diluted share, compared with the year-ago quarter when it recorded a gain from the sale of International Lease Finance Corp.

AIG’s stock closed at $64.14 on the New York Stock Exchange on Monday.