Shares of Qualcomm tumbled Monday after a downgrade on the back of potential legal troubles.
On Monday, Nomura's Instinet lowered its rating on the chipmaker's stock to neutral from buy on concerns about how the scrutiny on royalties would affect Qualcomm's deal to acquire NXP Semiconductors.
Qualcomm shares dropped more than 11 percent in midday trade, tracking for its biggest decline since Nov. 5, 2015, when shares fell 15.25 percent.
Shares of NXP Semiconductors traded more than 1 percent lower. The iShares PHLX Semiconductor ETF (SOXX) traded 0.5 percent lower.
Qualcomm did not immediately respond to CNBC's request for comment.