By Anshuman Daga and Manolo Serapio Jr SINGAPORE, Jan 22 (Reuters) - Singapore Exchange Ltd, set to report its weakest profit in more than a year after a penny stock scandal hammered trading volumes, is placing a big bet on an increasingly crowded derivatives market. The demise of SGX mini metals contracts, and lower volumes for its iron ore swaps since China launched a competing product, could be a warning sign for its ambitions as major international exchanges muscle into its home turf. The exchange is set to report second-quarter net profit of S$75.2 million ($58.94 million) on Wednesday, down 1.4 percent from a year ago, according to a Reuters poll of eight analysts. Since taking over as CEO four years ago, Magnus Bocker has spearheaded the launch of new financial and commodity derivatives to make Singapore a regional gateway in Asia.