The downgrade to Underweight suggests a bearish outlook on Ally Financial's stock by JP Morgan, indicating a potential decrease in stock price in the short term. However, the increase in price target to $39, up from $37, adds a layer of complexity, suggesting that while the stock might face downward pressure, its valuation might still be seen as slightly more favorable than previously thought. The net effect is likely negative due to the weight of a downgrade in investor sentiment.