(Updates market action and adds analyst's comments)
* TSX down 166.53 points, or 1.19 percent, at 13,870.1
* Nine of the TSX's 10 main groups fall
By Solarina Ho
TORONTO, Aug 20 (Reuters) - Canada's main stock index sank more than 1 percent on Thursday, hitting the lowest level of the year, as investor concern about prospects for global economic growth continued to cast a pall over markets.
The TSX index was on track for its ninth decline in 11 sessions, with most of its main sectors giving up 1 to 2 percent by late morning.
"It's really, really ugly," said Paul Taylor, chief investment officer of asset allocation at BMO Asset Management. "The global economic backdrop is not particularly robust. And Canada's just getting crushed by oil."
Royal Bank of Canada was among the heaviest drags on the index, shedding 1.8 percent to C$74.37. Toronto-Dominion Bank was not far behind, declining 1.1 percent to C$51.38.
The index's hefty financial group, which has been squeezed by a low interest rate environment and its close ties with commodities-related companies, retreated 1.2 percent. Banks are also coming into the spotlight ahead of quarterly earnings reports next week.
At 11:34 a.m. EDT (1534 GMT), the Toronto Stock Exchange's S&P/TSX composite index was down 166.53 points, or 1.19 percent, at 13,870.1.
Declining issues outnumbered advancers by about a 3-to-1 ratio, with stocks on the index posting one new 52-week high and 42 new lows.
Energy stocks, which have fallen more than 11 percent through eight straight sessions of declines, were trading at the lowest levels since 2004.
The group was down 0.6 percent as U.S. crude prices, which have sunk as low as $40.21 a barrel on worries of a global glut and softening demand, remained around C$41.
In the sector, Enbridge Inc fell 2.0 percent to C$52.74.
Taylor said any index turnaround will hinge on the price of oil and believes prices will remain weak through the end of this year before bottoming and firming sometime in the first quarter of 2016.
The materials group was the lone gainer among the index's top 10 sectors, rising 1.2 percent as gold miners in particular were burnished by bullion prices that hit their highest level in five weeks on safe-haven buying.
Barrick Gold Corp surged 6.2 percent to C$10.98 while Goldcorp Inc climbed 2.7 percent to C$20.39.
The always volatile Valeant stock of Valeant Pharmaceuticals International Inc tumbled 3.4 percent to C$309.29 after the company said it would buy Sprout Pharmaceuticals, maker of the first approved treatment for low sexual desire in women, for about $1 billion plus milestone payments. (Reporting by Solarina Ho; Editing by Peter Galloway)