Canadian stocks headed lower Tuesday, as traders stayed wary ahead of a meeting by the U.S. Federal Reserve this week.The S&P/TSX composite index dropped 20.90 points to 15,461.66.The loonie was up 0.31 of a cent to 90.81 cents US, as the latest data showed that Canadian manufacturing sales in July handily beat analysts’ expectations.Statistics Canada said sales rose 2.5 per cent to $53.7 billion in July, exceeding the previous record of $53.2 billion set in July 2008. Economists had expected a gain of one per cent, according to Thomson Reuters.Wall Street was mainly weak with the Dow Jones industrials fading 12.33 points to 17,018.81, the Nasdaq was ahead 1.22 points to 4,520.12 and the S&P 500 index gained 0.35 of a point to 1,984.49.Specifically, markets will be looking to see if the statement released by the Fed following its meeting will contain any hints on when the central bank will raise interest rates and if this move will be sooner than mid-2015, which has been widely anticipated. Short-term rates have been near zero since the financial collapse of 2008-09.For some time, the Fed has reassured markets that “it likely will be appropriate to maintain the current target range for the federal funds rate for a considerable time after the asset purchase program ends.” Markets will look to see if the Fed drops the words “considerable time” in the announcement.Overseas, there continues to be uncertainty over the outcome of the upcoming referendum in Scotland. With just two days to go until the vote, anti-independence supporters argue that separation would cause economic uncertainty, while yes supporters accuse the no side of scaring voters. Most think the outcome is too close to call at this point.A yes vote would result in huge complications from currency to membership in the European Union and NATO.In corporate news, an investment group that includes Wind Mobile founder Tony Lacavera and Canadian private equity firm West Face Capital has a tentative deal to buy out Wind’s majority shareholder, VimpelCom Ltd., a Russian-Dutch company that has been trying to exit the Canadian market since it was blocked from gaining full ownership of the small wireless carrier last year. Financial terms of the deal were not released.Lacavera, who owns about 35 per cent of Wind Mobile through Globalive, has been attempting to position it as a significant competitor to Canada’s three biggest carriers, which collectively have about 90 per cent of the total wireless subscriber base.Wind currently has about 750,000 customers, or less than 10 per cent of any of the Big Three: Rogers (TSX:RCI.B), Telus (TSX:T) and BCE’s Bell (TSX:BCE). The telecom sector on the TSX was down 0.30 per cent.Meanwhile, Allergan and Pershing Square have agreed on a step toward settling a fight over the makeup of the Botox-maker’s board. Allergan will hold its special shareholders meeting as planned on Dec. 18, while Pershing Square and its partner, Valeant Pharmaceuticals, continue their push for control of the California-based rug company.Valeant, based in Laval, Que., has made several offers to buy Allergan, the latest bid coming in at US$53 billion. Shares in Valeant (TSX:VRX) dipped 0.45 per cent to $133.59.On the commodity markets, the October crude contract on the New York Mercantile Exchange gained 63 cents to US$93.55 a barrel. December bullion was up $1.30 to US$1,236.40 an ounce, while December copper was up a penny to US$3.09 a pound.