The increase in the price target from $145 to $155 by Evercore ISI Group indicates a positive outlook on Ryanair Holdings' stock performance in the short term. This adjustment suggests that the analyst sees potential for growth or positive momentum in the company's stock price, likely due to favorable market conditions, operational performance, or strategic initiatives that could enhance shareholder value. Investors may view this as a bullish signal, potentially leading to increased buying interest and a positive impact on the stock price in the short term.