Economies of scale and mergers of equals become the M&A mantras in 2009, and niche investment banking boutiques such as Evercore (EVR), Lazard (LAZ) and Greenhill (GHL) flourish. Goldman Sachs and Citigroup announce a merger of equals, but Goldman maintains management control of the combined entity. Morgan Stanley (MS) acquires Blackstone. Disney (DIS) purchases Carnival (CCL). Microsoft (MSFT) acquires Yahoo! (YHOO) at $5 a share.