Shares in casual dinning chain Cheesecake Factory Inc. dropped 2 percent Thursday after shares in the company were downgraded by Credit Suisse.

Analyst Keith Siegner also downgraded fast food company Sonic Corp., warning that both restaurant chains may face challenges from weaker demand and higher costs.

Shares in Cheesecake Factory Inc. were down 2 percent to $16.93 in early trading Thursday. A slumping economy and rising gas prices have hit causal dining restaurants hard this year, sending shares in Cheesecake Factory down nearly 30 percent.