The S&P/TSX composite index gave back 16.41 points to 14,960.51. A string of reverses this month centred on economic worries and the timing of future rate hikes resulted in the main Toronto index chalking up a 4.26 per cent loss, its first monthly decline in four months.
The Canadian dollar was down 0.37 of a cent to a fresh, six-month low of 89.29 cents US.
Statistics Canada reported that gross domestic product was flat during July following a 0.3 per cent rise in June, below an expected gain of 0.2 per cent.
U.S. indexes were lower amid other data showing deteriorating consumer confidence. The New York-based Conference Board's index fell to 86 during September from 93.4 in August.
The Dow Jones industrials were down 28.32 points to 17,042.9, ending the month with a small loss. The Nasdaq declined 12.46 points to 4,493.39 while the S&P 500 index shed 5.51 points to 1,972.29.
HSBC Corp.’s monthly purchasing managers’ index showed that China’s manufacturing activity in September held steady at the previous month’s low level, indicating the world’s second-largest economy faces risks to growth. The index came in at 50.2. Anything below 50 indicates contraction.
Other Chinese data this month reported declining industrial production, lower property prices, weaker imports and pressure on factory prices, all of which added to concerns that outside of the U.S., global growth is faltering badly.
"Without a doubt, we have slowing global economies and part of that is a deterioration in the rate of growth in China," said Tim Caulfield, co-lead manager of the Franklin Bissett Canadian Equity Fund. "And we have seen that weigh heavily on energy and materials equities in September."
Traders have also been concerned that an improving American economy could persuade the U.S. Federal Reserve to move on raising interest rates sooner than expected next year.
Positive U.S. economic data and Fed speculation have also helped strengthen the U.S. currency, which in turn have depressed commodity prices during September.
A stronger greenback makes it more expensive for holders of other currencies to buy oil and metals, which are U.S.-dollar-denominated.
The TSX is still up about 10 per cent for the year as Caulfield observed that the TSX has registered gains in 11 of the past 12 months.
"So when we do see a pullback, it’s not entirely surprising given the extent of the advance that we have seen in the current bull market."
The energy sector fell 0.8 per cent while November crude in New York tumbled $3.41 to US$91.16. Lower demand and a glut of supply sent oil tumbling five per cent this month to its lowest closing price since November 2012.
The base metals sector on the TSX was down 0.6 per cent while December copper gave back five cents to US$3.01 a pound as lower demand pushed the metal, viewed as an economic barometer, down five per cent this month.
The gold sector moved down 1.35 per cent as December gold faded $7.20 to US$1,211.60, losing almost six per cent this month amid low inflation readings in most parts of the globe.