The S&P/TSX composite index lost 35.29 points to 15,164.97, with the energy and gold sectors also contributing to the decline.
Bank of Montreal (TSX:BMO) posted lower earnings amid an "unsettled environment" that saw the bank deal with "significant movements in oil prices, long-term interest rates and the Canadian dollar."
Adjusted net income was $1.04 billion or $1.53 a share, a dime short of estimates and its shares closed down $1.55 at $75.83. Most other bank stocks were also lower with traders anticipating similar issues when the remainder of the country's six major lending institutions report this week and next.
"Across the rest of the Canadian banks, we will see a lacklustre or challenging or slower growth environment from personal and commercial banking," said Colum McKinley, Canadian equities manager at CIBC Asset Management.
The Canadian dollar was up 0.51 of a U.S. cent at 80.03 cents.
U.S. indexes were higher as Yellen told the Senate finance committee that the U.S. central bank would continue to be patient in deciding when to hike interest rates. And she added that before rates go up, the central bank would drop this assurance.
There has been much speculation the bank could move on raising rates as early as June.
"Over time, if the U.S. economy continues to accelerate, we will inevitably get to the point where rates will move higher," McKinley said, "but the Fed is still managing that process of setting expectations around when that could happen and what it would look like."
The Dow Jones industrials gained 92.35 points to 18,209.19, the S&P 500 index edged up 5.83 points to 2,115.49 and the Nasdaq rose 7.15 points to 4,968.12.
TSX gains were paced by a 3.4 per cent jump in the base metals sector as March copper was up six cents at US$2.65 a pound.
The TSX energy sector surrendered early gains to move down 0.63 per cent as oil lost 17 cents to US$49.28 a barrel.
The gold sector was off 1.25 per cent as April bullion faded $3.50 to US$1,197.30 an ounce.
Canadian National Railway (TSX:CNR) arrived at a tentative agreement Monday with Unifor, which represents about 4,800 mechanical, intermodal and clerical workers, less than an hour after the railway’s 11 p.m. ET deadline to lock out the union's members. CN declined 13 cents to $86.59.
Fertilizer company Agrium Inc. (TSX:AGU) turned in quarterly net earnings of US$51 million or 33 cents a share, down from US$99 million or 66 cents in the same 2013 period. Sales revenue fell by US$162 million to US$2.7 billion from just under US$2.9 billion. Its shares ran ahead $4.06 to $142.08.
There was also positive news for the eurozone. Greece's creditors in the 19-country currency union approved a list of reforms Athens proposed to get a four-month extension to its bailout, which should keep the country afloat over the coming months.