Swiss bank UBS AG reported better-than-expected third-quarter net profit Tuesday as an accounting gain helped cancel out the 1.849 billion Swiss franc loss on unauthorized trades it uncovered last month.

Net profit fell to 1.018 billion francs, compared to average analyst forecasts for 276 million francs and steady from the 1.0 billion francs it posted in the second quarter, already hit by falling trading volumes.

It said a 1.765 billion franc gain on the value of its own debt helped make up for the 1.849 billion trading loss and 387 million francs of restructuring costs it booked after announcing 3,500 job cuts in August.

This accounting gain -- which occurs because the bank could profit from buying back its own bonds at lower levels -- also gave a big boost this quarter to profits at most U.S. banks.

However, UBS results also mirrored their U.S. peers in showing declining bond and stock revenues as sovereign debt worries spiraled in the three months to September.

(Reporting by Emma Thomasson)