* TSX index finishes down 86.35 points at 9,762.85

* Index falls 4.6 percent on the week

* Energy sector, down 2.48 percent, leads TSX lower

* Technical glitch disrupts data feeds for an hour (Adds details, quotes)

By Jennifer Kwan

TORONTO, May 15 (Reuters) - Toronto's main stock index erased an early gain and closed lower on Friday as energy shares fell with oil prices, which dropped further from the six-month high they reached earlier this week.

The index's energy sector fell 2.48 percent as the price of oil settled lower at $56.34 a barrel, due in part to weak global demand. [ID:nSIN460588]

Suncor Energy (SU.TO: Quote, Profile, Research), the biggest drag on the index, dropped 2.8 percent to C$33.67, and Canadian Natural Resources (CNQ.TO: Quote, Profile, Research) was down 2.7 percent to C$57.96. EnCana (ECA.TO: Quote, Profile, Research) dropped 1.8 percent to C$59.23.

With the financial sector down 0.91 percent on Friday, and the mining-heavy materials group off 0.8 percent, it appeared investors were reassessing the recent run-up in stock markets, said Elvis Picardo, analyst and strategist at Global Securities in Vancouver. The TSX index has risen about 30 percent from its March lows.