Story updates at 10 a.m. to reflect market activity.
Shares of GT Advanced gained 3.9% to $17.64 in morning trading.
The analyst firm raised its price target for the company to $24 from $18. Credit Suisse noted that prices for polysilicon and sapphire are rising. Progress on GT Advanced's supply agreement with Apple (AAPL) also contributed to the upgrade.
Must read: Warren Buffett's 10 Favorite Dividend Stocks