"The overvalued Swiss franc dampened growth in the first half of the year,"Swatch said in its first half report.
"As in the previous year, the first half of 2017 was characterized by worldwide turbulence," the report said.
"However, the Swatch Group, with its 20 strong brands and its own retail network, is very well represented worldwide, and was therefore able to generate net sales of 3.7 billion Swiss francs (3.3 billion euros, $3.9 billion)."
That represented a fractional decline of 0.3 percent compared with the corresponding period a year earlier.
At constant exchange rates, sales would have risen by 1.2 percent.
Net profit grew by 6.8 percent to 281 million Swiss francs (254 million euros), slightly short of analysts' expectations.
Looking ahead, Swatch said it "anticipates very positive growth in local currency in the second half of the year. In addition to its already strong own retail business, wholesale should also develop positively".