The company, which pays a dividend equal to 20 per cent of the cash generated by operating activities, said it would pay a fourth-quarter dividend of seven cents per share, down from 10 cents in the third quarter.
"While overall production was strong, payable silver equivalent ounces produced but not shipped during the quarter increased by two million ounces due to the timing of concentrate shipments, negatively affecting silver equivalent sales volume," Silver Wheaton president and chief executive Randy Smallwood said.
"It is very important to remember that these ounces will inevitably be sold, it is simply a matter of timing."
The Vancouver-based company, which reports in U.S. currency, said Monday it earned a net profit of US$119.7 million or 34 cents per share compared with US$135 million or 38 cents per share in the third quarter of 2011.
The drop for the three months ended Sept. 30, came as revenue totalled US$161.3 million, down from US$185.2 million a year earlier and down from $201.4 million in the second quarter of 2012.
Cash flow from operations in the third quarter was US$128.7 million or 36 cents per share, down from US$172.9 million or 49 cents per share in the second quarter this year and down 23 per cent from a year earlier in the third quarter of 2011.
Production in the quarter amounted to 7.7 million silver equivalent ounces, up from 6.1 million ounces a year ago, while due to the timing of deliveries sales totalled 5.1 million about the same as a year ago.
However, the average realized silver price fell 13 per cent to $31.36 per silver equivalent ounce for the quarter, down from $36.23 in the third quarter of 2011.
Silver Wheaton's expenses also went up, with the average cash cost rising four cents an ounce to US$4.16.
BMO Capital Markets analyst Andrew Kaip called the results mixed, but noted that the deferred silver sales could set the company up for a strong fourth quarter.
"While production was broadly in line with BMO Research's expectations, sales were markedly lower, highlighting quarter-over-quarter volatility in Silver Wheaton earnings that are dependent on the timing of metal sales," Kaip wrote in a report.
RBC Capital Markets analyst Dan Rollins said the results were weak, but did not raise long-term concerns.
"With over $1 billion in available funding expected to be on hand at year end, Silver Wheaton remains well positioned to pursue additional accretive acquisitions," Rollins wrote in a note to clients.
Silver Wheaton's stock fell by as much as C$1.18 per share on Monday but regained much of the loss later in the session. The shares closed down 57 cents at C$38.88.