Amgen on Sunday announced an additional investment of $421 million in Chinese biotech Beigene, adjusting its stock ownership to 20.3 percent.

The Thousand Oaks company initially invested $2.7 billion in cash for 20.5 percent ownership of Beigene in October.

In a statement, Amgen said its additional investment “reflects Amgen’s confidence in the progress the companies are making in their ongoing oncology collaboration in China,” referring to the companies’ agreement to advance 20 medicines from Amgen’s pipeline.

Beigene also agreed to commercialize Amgen drugs Xgeva, Kyprolis and Blincyto in China as part of the collaboration.

Shares of Amgen (AMGN) closed Monday up $1, or a fraction of a percent, to $250.04 on the Nasdaq.