The death knell for corporate America’s greatest individual experiment in mergers and acquisitions sounded in November 2021 when General Electric announced its intention to split in three. A thousand deals were struck by Jack Welch, its notoriously gung-ho boss who ran the American industrial and financial giant between 1981 and 2001, a pace that did not slacken under his successor, Jeffrey Immelt. The result has been a monumental…