The irrational exuberance that surrounded Apple shares last fall has apparently shifted over to Google. Google shares closed trading on Monday at an all-time high of $861.55, giving the company a total market cap of $285.8 billion. The surge in its share price Monday has left Google as the world’s second most valuable tech company, edging out Microsoft’s $281.9 billion market cap but still significantly trailing Apple’s $433.1 billion market cap. The rise in Google’s shares over the past few months has led to several analysts assigning the company’s stock a $1,000 price target based on optimism that the success of its Android platform will spread Google services to a wide range of markets throughout the world.