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Shadow Boxing the Market: Option Pricing Without a Safe Haven

TL;DR for operators Discounting is the quiet plumbing of derivatives. Most option-pricing systems assume a risk-free asset sits somewhere in the background, calmly providing the rate at which future payoffs become present prices. This paper asks what happens when that safe haven is unavailable, unreliable, or merely too theoretical to be useful. Its answer is not to abandon discounting, but to manufacture it from the relative dynamics of two risky assets.1 ...

August 3, 2025 · 16 min · Zelina
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Beyond the Mean: Teaching RL to Price the Entire Option Distribution

TL;DR for operators Pricing desks usually ask an exotic-option model for one number: the expected discounted payoff. The paper behind this article asks for the whole conditional payoff distribution instead.1 That sounds like a small statistical upgrade. It is not. It changes what the model is trying to learn, what risk information becomes available after training, and where the engineering fragility enters. ...

July 20, 2025 · 17 min · Zelina
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Residual Learning: How Reinforcement Learning Is Speeding Up Portfolio Math

TL;DR for operators Financial AI is usually sold as a machine that predicts markets. This paper is about something more modest and, frankly, more useful: making the maths underneath portfolio optimisation and option pricing run faster. The authors propose a reinforcement learning controller that adjusts the block size of a preconditioner inside Flexible GMRES, an iterative solver used for large sparse or awkward linear systems. The agent is trained with PPO. Its state is the current residual vector, its action is a choice of block size, and its reward pushes the residual norm downward. In plain English: the model watches how badly the solver is still missing the answer, then changes the way the solver reorganises the problem. ...

July 6, 2025 · 13 min · Zelina