Economic Definition of Tobin's Q. Defined.
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Term Tobin's Q Definition: A financial measure of a firm's returns, calculated by dividing the market value of the firm (that is, the market value of its outstanding stock and debt) by the replacement costs of the firm's assets. According to James Tobin of Yale University, Nobel Laureate in Economics in 1981, if this ratio is greater than 1 it means that the firm is earning a rate of return higher than that justified by the costs of its assets. That is, Tobin suggested that the ratio of the market value of a firm to the replacement costs of its assets should be close to 1.