Bayer AG (BAYRY)  shares rose to the top of the German leaderboard Thursday after reporting better-than-excepted first quarter earnings that were boosted by a near 20% advance in sales of the group's Xarelto stroke prevention treatment.

The German drug and pesticides maker, which is in the midst of completing a $66 billion takeover of Monsanto (MON) , beat analysts' estimates reported adjusted operating profit of €3.9 billion ($4.2 billion) a 15% increase compared with last year and beating average estimate of €3.6 billion in a Reuters poll of analysts.  Sales at the group level increased 11.7% to €13.24 billion in the three months to the end of March, the company said.

"At Pharmaceuticals, we once again benefited from the very good performance of our key growth products," CEO Werner Baumann said in a statement.

Bayer shares jumped 2.7% in the opening minutes of trading in Frankfurt to change hands at €110.65 in the first hour of trading Thursday, sending it to the top of Germany's DAX. The Stoxx Europe TMI Pharmaceuticals Index has gained 5.4% since the start of the year.

Bayer also saw strong sales in its pharmaceuticals, with sales up 7.4% to €4.3 billion. "Our key growth products were once again especially successful, registering combined growth of 20 percent on a currency-adjusted basis," Baumann said.

These products are oral anticoagulant Xarelto, eye medicine Eylea, cancer drugs Xofigo and Stivarga, and the pulmonary hypertension treatment Adempas posted total combined sales of €1.45 billion.

Sales of Xarelto climbed by 19.6% on a currency-adjusted basis, due primarily to higher volumes in Europe and Japan.

Operating profit before special items of pharmaceuticals increased by a substantial 19.1% to €1.5 billion. Selling expenses and research and development expenditures were at around the same level as the prior-year quarter.

The group also saw good sales at Covestro, its former material science division which is now listed separately. Sales advanced by 23.6% to €3.6 billion, due to higher selling prices.

Bayer said it now expects sales for the year of €51 billion rather than €49 billion and Ebitda before special items to grow by a "low teens percentage" rather than a "mid-single digit percentage".