Why Are Tandem Diabetes Shares Falling Premarket Today?

Tandem Diabetes Care Inc TNDM reported Q3 sales of $179.6 million, +45% Y/Y, beating the consensus of $171.41 million.
The Company posted EPS of $0.09, a turnaround from a loss of $(0.15) and beating the Wall Street estimate of $0.06.
Worldwide pump shipments increased 43% Y/Y to 31,558 pumps, but lower than 33,817 reported in Q2 FY21.
Gross margin improved to 54% from 53%, and operating margin improved to 4% from negative 1%.
Domestic pump shipments increased 10% to 20,296 pumps, slightly above 20,665 in Q2 FY21. Domestic sales were $133.1 million, +24%.
International pump shipments increased to 11,262 pumps, but lower than 13,152 in Q2 of FY21. International sales increased 189% to $46.5 million.
Tandem Diabetes ended Q3 with cash, cash equivalents, and short-term investments of $595.0 million.
Guidance: Tandem forecasts sales of $685 million - $695 million (consensus of $684.32 million), compared to prior guidance of $670 million - $685 million.
The Company sees International sales of approximately $168 million - $173 million, higher than prior guidance of $160 million - $165 million.
Price Action: TNDM shares are trading lower by 10.2% at $127.01 premarket on Thursday.