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Advanced Proof

Girsanov's Theorem: Transforming Measures for Risk-Neutral Valuation

Students often struggle to distinguish between the 'change of measure' and a mere coordinate transformation. Crucially, Girsanov's Theorem does not change the sample paths of Wt W_t , but rather changes the probability assigned to those paths, effectively absorbing the drift into the measure itself.
Institutional Reference: Advanced Stochastic Processes
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