His first textbook was on option theory.

FORBES: Magazine Article

The theory views equity as a call option on a firm's assets.

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But, in theory, Barclays, Standard Chartered and HSBC have the option of paying a lower amount by moving their respective domiciles, their homes, offshore (to be clear, they'd still have to pay a fair whack, because they would still have taxable debt in the UK).

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In theory, at least, each of the city's 80, 000 eighth graders has the option of going to any one of 700 high school programs.

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