Canadian markets closed slightly higher Friday as the price of oil moved past the US$45 a barrel level, while U.S. stocks were hit by a surprise announcement from drug giant Pfizer Inc.

At close, the S&P/TSX was up 5.98 points or 0.07% to 9122.62 for a gain on the week of 1.8%. The TSX Venture exchange added 11.66 points or 0.68% to 1738.63. The Dow Jones lost 55.72 points or 0.52% to 10649.92 for a 1% increase on the week. The Nasdaq dipped 10.95 or 0.51% to 2135.20 and the S&P 500 lost 8.99 or 0.75% to 1194.22.

The Canadian dollar moved 0.40 of a cent higher to US81.49¢.

In Toronto, energy stocks, metals and materials were the only sectors in the black. Energy stocks were up 0.86% on another jump in the price of oil. The price of light, sweet crude on the Nymex rose $1.47 to US$45.65 a barrel on concern over heating oil inventories.

On Wall Street, stocks dropped in very heavy trading Friday as fresh concerns about pharmaceuticals, coming after Pfizer announced a troublesome health study of its Celebrex drug, overshadowed news of subdued growth in consumer prices and inflation.

Just before the start of the session, Pfizer said a new study showed people taking high doses of Celebrex, the best-selling arthritis drug, had an increased risk of heart troubles. A similar revelation led to the removal of Merck & Co.’s competing Vioxx drug earlier this year — and led to a major selloff of Merck shares. Pfizer said it will leave Celebrex on the market.

Shares of Pfizer fell 10.97% to US$25.80. More than 289 million shares of Pfizer traded hands by late afternoon, far outstripping the recent average daily volume of 33 million shares per day.

Despite moderate losses during the session, analysts remained bullish on the overall market.

The markets were volatile due to a “quadruple-witching” day on Wall Street — the quarterly expiration of index futures and options, as well as individual stock futures and options. Stocks can vary widely and trade quickly on heavy volume as investors cash in their options or futures and sign up for new contracts.