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HardStochastic Processes

Expected Running Max of BM

Goldman SachsDE Shaw

For a standard Brownian motion, what is the expected value of its running maximum over [0, 1], i.e. E[max0t1Bt]\mathbb{E}[\max_{0\le t\le 1} B_t]? (Round to 3 decimals.)

Hints

Reflection principle: the running max is distributed like Bt|B_t|.

E[Z]=2/πE[|Z|] = \sqrt{2/\pi} for standard normal.

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