AOL and Time Warner

In January 2000, AOL and Time Warner announced a merger valued at roughly $165 billion, dial-up's hottest stock fused with the most prestigious content library in media. On paper the logic was clean: AOL's distribution would carry CNN, HBO, and Warner Bros. to a new generation. Within a year the dot-com bust hit, AOL's inflated stock collapsed, broadband made its core obsolete, and the combined company wrote down about $99 billion. By 2009 the whole thing was spun off for a fraction of its peak.

This is the deal MBA programs still autopsy, and for good reason. The synergy spreadsheet was the easy part; what broke ran deeper than any model captured. For any operator weighing an acquisition, a merger, or even a big partnership, the case sharpens the questions you ask before you sign, not after. It shows you where the bodies were buried without telling you which shovel did it.