ASML is tumbling Monday, set for their steepest drop since June, after reports China is making its own immersion lithography machines.

A Shanghai-based company has begun making immersion DUV lithography machines, The Information reported. ASML shares dropped 6.5%. China's share of ASML sales fell to 14%.

ASML stock tumbled on a report of competition emerging in China. It was among the biggest losers on the Philadelphia semiconductor index.