TSX Today: What to Watch for in Stocks on Tuesday, May 19

The Canadian stock market fell sharply ahead of the long Victoria Day weekend as investors reacted to escalating geopolitical tensions while West Texas Intermediate (WTI) crude oil futures traded above US$103 per barrel amid ongoing disruptions around the Strait of Hormuz. The S&P/TSX Composite Index plunged by 435 points, or 1.3%, to settle at 33,833, marking its worst single-day decline in nearly three weeks.

Despite positive movement in tech stocks, sharp declines in other key market sectors, including healthcare, mining, and consumer cyclicals, pressured the TSX benchmark.

Top TSX Composite movers and active stocks

Curaleaf Holdings, Wesdome Gold Mines, Taseko Mines, and Aya Gold & Silver were the worst-performing TSX stocks for the day, as they plunged by at least 9.8%.

Shares of Allied Gold (TSX:AAUC) also fell by 3.3% to $s38.89 apiece, making it among the day’s bottom performers on the Toronto Stock Exchange. This selloff in AAUC stock came after the gold miner posted a first-quarter 2026 net loss of US$58.3 million compared to a profit of US$15.1 million a year ago, despite stronger production and revenue growth.

Allied Gold’s quarterly revenue still jumped nearly 14% YoY to US$394.1 million as its gold production rose 14% to 96,016 ounces, helped by stronger output from its Bonikro and Agbaou mines. However, investors appeared concerned about rising operating costs, with all-in sustaining costs climbing to US$2,264 per ounce from US$1,811 a year ago amid higher royalties and operational expenses.

On the brighter side, Bird Construction, Strathcona Resources, Stantec, and Quebecor climbed by at least 5.3% each, making them the session’s top-performing TSX stocks.

Based on their daily trade volume, Enbridge, Manulife Financial, Americas Gold and Silver, Suncor Energy, and Barrick Mining were the five most active stocks on the exchange.

TSX today

WTI crude oil futures prices trended higher in early trading on Tuesday, while metals prices across the board fell. Given these mixed commodity trends, the resource-heavy TSX index could see a volatile start to the session, with gains in energy stocks potentially offset by weakness in mining shares.

Canadian investors may also react to fresh Canada-U.S. defence tensions after the Pentagon paused participation in the Permanent Joint Board on Defence, citing Canada’s slow progress on military spending commitments. For TSX investors, this development may keep defence, infrastructure, aerospace, and industrial stocks in focus, especially companies exposed to government contracts or cross-border supply chains.

Market movers on the TSX today

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