So it was a mystery, argued Messrs Modigliani and Miller in 1963, why firms did not finance themselves almost entirely with debt.

ECONOMIST: A survey of Corporate Finance

In 1958 professors Franco Modigliani and Merton Miller showed that this kind of thinking is wrong.

FORBES: Magazine Article

But in 1958 Franco Modigliani and Merton Miller, two American economists, showed that the value of a firm should be unaffected by whether it is financed using all debt, all equity, or a mix of the two.

ECONOMIST: Stocks in trade | The

Merton Miller and his colleague Franco Modigliani posited their capital structure irrelevance theorem in the late 1950s, when the dollar was as good as gold at least for foreign creditors.

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