Insurer Ace Ltd reported a quarterly profit that beat analysts' estimates as commercial insurance rates continued to improve in the United States.The company's net income fell 2.1 percent to $953 million, or $2.77 per share, for the first quarter from $973 million, or $2.84 per share, a year earlier.However, per-share earnings of $2.17 per share significantly topped analysts' expectations. Analysts on average had expected operating income of $1.94 per share, according to Thomson Reuters I/B/E/S.Revenue decreased 9.25 percent to $3.8 billion from the year earlier quarter.The Swiss company raised its full-year outlook, now expecting operating income of $7.10 to $7.50 a share, from its downbeat January prediction of $6.60 to $7 a share.ACE was acquisitive last year, buying Ally Financial Inc.'s Mexican insurance arm ABA Seguros and New York Life Insurance Co.'s surety writer Fianzas Monterrey, also in Mexico. It also purchased Jakarta-based general insurer PT Asuransi Jaya Proteksi.Two weeks ago, the company said it formed an agriculture property and casualty insurance business, ACE Agribusiness, which is comprised of two previously acquired businesses.Net premiums written rose 6.3 percent. Investment income declined 2.4 percent, mainly due to lower reinvestment rates offset by higher distributions from private equity funds.The property and casualty combined ratio — the percentage of each dollar in premiums paid out on losses and expenses — fell to 88.2 percent from 89.2 percent a year ago.Chief executive Evan Greenberg said the combined ratio was helped by strong current accident-year underwriting income that resulted from improved margin and growth in the company's US and international businesses.“ACE had an excellent first quarter and strong start to the year. We produced $746 million in after-tax operating income and our operating ROE was 12 percent, driven by strong underwriting results,” Mr Greenberg said.“Premium revenue growth across the company was very good, with total net premiums up over six percent. We are taking full advantage of the improved commercial P&C pricing environment in the US and our strong presence in areas of the world where economic fundamentals are superior, such as Asia and Latin America,” Mr Greenberg added. “We are optimistic about our growth prospects for the balance of the year.”Shares rose 17 cents to $89.44 after hours. The stock up 19 percent over the past 12 months.