Change in Ratings AK Steel ( AKS) downgraded at Goldman Sachs to Sell from Neutral based on significant ownership by hedge funds, fixed cost structure and high sensitivity to steel prices. Note high exposure to auto markets and to contract business and believe hedge-fund selloff may add pressure. Price target cut to $15 from $53. CACI International ( CAI) downgraded at JP Morgan from Overweight to Neutral. Valuation call. Stock has been the best performer in the group, and is subject to changing political winds. Commercial Metals ( CMC) upgraded at Goldman Sachs to Buy from Neutral based on valuation. Note company's diversified business model, vertical integration and geographic diversification. Price target cut to $13 from $36. Dynegy ( DYN) downgraded at UBS to Neutral from Buy. Fiscal 2009 EPS estimates lowered to 19 cents from 28 cents. Price target lowered to $2.50 from $8. Harris ( HRS) upgraded at JP Morgan from Underweight to Neutral. Stock has underperformed and is already pricing in a slowdown in the RF business. Eli Lilly ( LLY) downgraded at Credit Suisse to Neutral from Outperform. Says ImClone deal increases risk profile and sees challenges ahead. Lowered target price to $42 from $56. Pactiv ( PTV) upgraded at JP Morgan from Neutral to Overweight. Estimates also raised, to reflect the drop in resin prices. Company can grow earnings and gain market share despite the current environment. Ruby Tuesday ( RT) downgraded at Credit Suisse to Neutral from Outperform. Believes macro risks have increased markedly and balance sheet offers little room for error vs. guidance. Lowered target price to $9 from $11.