Upgrades by major financial institutions like Barclays often lead to positive investor sentiment and can result in a short-term increase in stock price. The upgrade from Equal-Weight to Overweight suggests a bullish outlook on ARRY by Barclays, and the increase in price target from $15 to $18 indicates a strong confidence in the company's future performance. This is likely to attract more investors to ARRY, potentially driving up its stock price in the short term.