PARIS — Swiss watch exports fell sharply in May, dragged down by calendar effects and a sliding sales in Hong Kong, the leading market for Swiss timepieces.

Exports for the month dropped 8.9 percent to 1.71 billion Swiss francs, or $1.84 billion, according to the Federation of the Swiss Watch Industry. This tipped the cumulative result since January into negative territory, with sales down 0.3 percent for the year so far.

“The month of May 2015 contained two fewer working days than May 2014, a fact which clearly held back watch exports,” the federation said.

Steel wristwatches led the decline, accounting for half the total drop in value and almost the entire reduction in volumes. Gold and bimetallic watches also contributed to the overall 6.2 percent decline in unit sales.

All price segments reported drops, with the downturn in volumes led by watches costing less than 200 francs, or $215. Exports of watches costing more than 3,000 francs, or $3,220, were down 14.2 percent, the federation reported.

Sales to Hong Kong, where pro-democracy protests have resulted in a sharp drop in Chinese tourists, plummeted 33.6 percent in May, reflecting a worsening picture in the beleaguered region.

Sales in China were down 9 percent, while the United States recorded a 13.7 percent decline, although the federation noted “the long-term trend here is very positive and robust.” Exports to Italy rose 4.5 percent, with the federation attributing the country’s ongoing momentum to the Universal Exposition in Milan.

Thomas Chauvet, analyst at Citi, said that although China now benefits from better comparatives, several negative factors remain: disruption in Hong Kong, a slowdown in the U.S., the potential impact of lower oil prices on demand from Russia and the Middle East, and the strength of the Swiss franc.

On the plus side, most European markets are proving resilient, reflecting tourist demand spurred by the weak euro and activity on parallel markets, he said.

“The deteriorating May data will be taken as a clear negative that watch industry trends are not improving in [the second quarter of 2015] in particular in Greater China,” he said in a research report.