TORONTO (Bloomberg) - Canadian stocks rose a fourth day, the longest winning streak in two weeks, as fertiliser makers advanced on speculation of an industry merger and Canadian Natural Resources Ltd. rallied on an analyst upgrade.

Crop nutrient producers Potash Corp. of Saskatchewan Inc. and Agrium Inc. added at least 4.5 percent after a Brazilian newspaper said Vale SA is preparing a takeover bid for Mosaic Co., North America's second-largest fertilizer producer. Potash companies fell earlier this week after a Russian producer agreed to cut Indian prices. Canadian Natural climbed three percent as CIBC raised the shares. Nexen Inc. dropped to the lowest price since March after the oil explorer missed analysts' profit forecasts.

"There was some concern about the profitability of potash," said Fred Ketchen, who oversees about C$100 million as managing director of equity trading at ScotiaMcLeod Inc. in Toronto. "Nobody else has joined in the price-cutting process, so that's given a little bit of enthusiasm to the current situation."

The Standard & Poor's/TSX Composite Index gained 88.96 points, or 0.9 percent, to 10,304.42 at 4.10 p.m. in Toronto. The benchmark index has surged 5.7 percent this week, and has climbed 36 percent since a five-year low on March 9.

Fertiliser companies led gains among material producers. Mosaic surged 12 percent in the US after O Estado de S Paulo said Vale is preparing a $25 billion bid. Potash Corp., the world's largest fertilizer producer by market value, advanced 4.6 percent to C$102.33, and Agrium added 5.3 percent to C$45.14.

Canadian Natural added three percent to C$61.56 as it rose for a sixth day, the longest winning streak since March. CIBC raised the shares to "sector outperformer", saying the shares are attractive given the long-term outlook for oil prices.

Nexen, which has operations in the North Sea and Yemen, slid 6.6 percent to C$21.62. The company reported second-quarter earnings excluding some items of 4 cents a share, missing the average analyst estimate by 86 percent, after oil prices tumbled and output slipped from its Buzzard and Syncrude projects.

Most Canadian banks declined on concern CIT Group Inc. will fail and credit-card losses will mount. CIT, the cash-strapped commercial lender, said it probably will not receive a US government bailout, raising concerns it may have to file for bankruptcy. Lenders also fell after JPMorgan Chase & Co. said its credit-card business is unlikely to make money in 2010.