Alejandro Rodriguez Dominguez · 2026-07-07
The paper reworks continuous-time portfolio optimization around a small set of underlying 'drivers' that make the assets independent, treating that driver structure (its geometry) as the true state of the problem instead of the individual assets. It shows the optimal strategy splits into a static allocation along the current driver geometry plus a hedging component that anticipates how that geometry predictably rotates and occasionally jumps over time. Because the driver set can change abruptly, some risk cannot be hedged by trading, making the market incomplete.
Why it matters: For practitioners running factor- or driver-based portfolios, this offers a formal argument that hedging changes in the factor structure itself (not just asset returns) is a first-order concern, and that computation scales with the number of drivers rather than assets. It also flags that shifts in which drivers matter create irreducible, unhedgeable risk — a caution against assuming a fixed factor model.
⚠ This is a theoretical continuous-time diffusion model illustrated only on synthetic economies, with no empirical or live-trading validation.
When a portfolio is conditioned on a minimal set of observable drivers under which its assets become mutually independent over the investment horizon, the dynamic investment problem acquires a distinctive geometric structure. We study continuous-time portfolio choice in this setting. The conditioning representation, rather than the asset vector, becomes the natural state of the problem, and it moves: the sensitivity of returns to the drivers depends on the state, the conditioning set may itself change over time, and the induced information geometry both rotates and, at discrete instants, jumps. The optimal policy separates into a static component that allocates along the conditioning geometry at each instant and an intertemporal component that hedges the predictable motion of that geometry, a first-order effect in the model rather than a refinement, placing the coordinates of the information geometry in the role played by exogenous state variables in classical intertemporal asset pricing. Because the problem is organized by the drivers, its computational cost is governed by their number rather than by the number of assets. Changes in the conditioning set generate a risk that continuous trading cannot span, so the market is incomplete in the direction of its own geometry. The analysis is carried out in a controlled diffusion model, and the resulting structure is illustrated on synthetic economies designed to isolate each mechanism.
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