* TSX down 42.08 points at 9,145.04
* Energy shares drop 2 pct to lead fall
* U.S. corporate earnings in focus (Adds details and comments)
By Frank Pingue
TORONTO, April 13 (Reuters) - Toronto's main stock index was lower on Monday morning as a slide in oil prices pulled energy shares down while some investors booked profits after a five-week string of gains.
The energy sector led the index lower with a 2 percent skid as the price of oil fell to around $51 a barrel after the International Energy Agency cut deeply its forecast for oil demand. [ID:nSP462067]
Shares of Suncor Energy (SU.TO) were down 2.5 percent at C$31.20, while Petro-Canada PCA.TO dropped 3 percent to C$38.37. Suncor and Petro-Canada shares were the two main drags on the index.
The lower start by the TSX index did not spur much concern since the index has rallied 21 percent over the past five weeks and the U.S. quarterly earnings season starts in earnest this week with a number of banks due to report results.
"It's just a just a little bit of normal profit-taking," said Sal Masionis, stockbroker at Brant Securities. "And people know the earnings are going to be very tough ... and the focus will be on what they are going to say about the future."
Key U.S. banks, which sparked an equity rally in early March when several said they were profitable in the first two months of the year, will report quarterly results this week and give investors a fresh insight into the health of the sector.
Bucking the downtrend on the TSX was a 2.4 percent gain by the materials sector, home to gold-mining companies, as the price of gold inched higher to hover above $850 an ounce.
At 10:00 a.m. (1400 GMT), the S&P/TSX composite index .GSPTSE was down 42.08 points, or 0.46 percent, at 9,145.04. Eight of the TSX's 10 subindexes were lower.
$1=$1.23 Canadian Reporting by Frank Pingue; editing by Peter Galloway