The Swiss stock market got off to a positive start Thursday, but slipped into negative territory around midday and remained there for the rest of the session. The weak performance of pharmaceutical heavyweights Novartis and Roche pressured the overall market.

The Swiss Market Index decreased by 0.42 percent Thursday and finished at 9,270.57. The Swiss Leader Index dropped 0.13 percent and the Swiss Performance Index lost 0.29 percent.

Roche ended the session lower by 2.0 percent, but had been down around 2.9 percent earlier in the session. The loss followed the release of disappointing study data on a new lung cancer combination therapy with Tecentriq and Avastin and chemotherapy.

Shares of Nestlé also finished lower by 0.4 percent.

Dufry declined 0.9 percent, Lonza fell 0.8 percent and Sonova lost 0.6 percent.

Schindler climbed 0.8 percent Swisscom gained 0.7 percent. Julius Baer was the top performer among the bank stocks, with an increase of 0.8 percent. UBS advanced 0.6 percent and Credit Suisse added 0.2 percent.

Aryzta rose 0.6 percent, adding to its gains from the previous session.

Logitech finished higher by 0.1 percent after UBS confirmed its “Buy” rating on the stock.