Much to the delight of the shareholders of Essex Property Trust Inc. ( ESS - Free Report ), Moody's Investors Service – the rating arm of Moody's Corp. ( MCO - Free Report ) – announced that it has upgraded the company's senior unsecured rating with a stable outlook. In fact, the rating agency has raised the senior unsecured rating of Essex Property from Baa2 to Baa1. Based in San Mateo, CA, Essex Property is a residential real estate investment trust ("REIT"), which is engaged in the acquisition, development, redevelopment and management of multifamily residential properties in supply constrained markets.