* TSX ends down 21.17 points at 11,489.63
* Remains up 53.6 pct from March's 5-year low
* Investors seen content to pocket gains (Adds details, comments and official numbers)
By Frank Pingue
TORONTO, Dec 7 (Reuters) - Toronto's main stock index ended lower on Monday as weighty energy shares fell alongside weaker oil prices, more than offsetting the boost the index got from Potash Corp (POT.TO) on an analyst upgrade of its shares.
Suncor Energy (SU.TO) shares, which headlined the selloff, fell 3 percent to C$36.76, followed by Canadian Natural Resources (CNQ.TO), which slid 2.4 percent to C$68.70.
Dragging energy stocks lower was a 2 percent slide in oil prices to below $74 a barrel as oil and product inventories rose in the United States as the economic downturn has depressed demand. [O/R]
Helping to cushion the slide was a rally in shares of fertilizer producer Potash Corp and its smaller rival, Agrium, after analysts raised their ratings on both companies. [ID:nN07161495]
Shares of Potash (POT.TO), the world's largest fertilizer maker, rose 3 percent to C$127.93, while Agrium's (AGU.TO) shares ended the session up 4.6 percent at C$63.79.
Minor advances or declines could become commonplace in the weeks ahead as investors opt to hang on to profits rather than take chances during holiday-thinned trade that will soon grind activity to a standstill.
The TSX is up 53.6 percent since stumbling in March to its lowest level in five years.
"With the performance the market has had this year, at least in the last nine months from the March lows, a lot of money managers are quite content just to have the year end right where it is," said Bruce Latimer, trader at Dundee Securities.
"They don't want to risk anything over the next two or three weeks and if anything they might trim some positions and be prepared to start fresh in the new year."
The S&P/TSX composite index .GSPTSE closed down 21.17 points, or 0.18 percent, at 11,489.63, its third straight lower close after rallying last week to its highest level in more than 14 months.
($1=$1.05 Canadian) (Editing by Peter Galloway)