Wells Fargo analyst David Maris downgraded Teva Pharmaceutical (TEVA) to Underperform with a $17 price target. The drugmaker closed yesterday up 45c to $19.58.

Teva shares have now risen approximately 80% from its lows in November, Maris tells investors in a research note. The analyst believes now is a good time to sell the stock. Other generic Copaxone's will emerge in 2018, pricing pressures will remain, and Teva's debt will be downgraded, Maris predicts.

The analyst lowered his 2018 earnings per share estimate to $2.68, well below the consensus at $3.00.