Atlas Asset Management · ZISIF §15

Single Asset
Impact

QUANTIFY HOW A SINGLE NAME
PROPAGATES INTO PORTFOLIO RETURN
R_P = w₁ × R₁ + (1−w₁) × R_REST
INPUTS BELOW · LIVE OUTPUTS ON RIGHT

Simulator · drag to explore

Parameters

Observed asset weight 20%

w₁ — share of portfolio

Observed asset return −25%

R₁ — performance of the observed name

Rest of portfolio return +3%

R_rest — performance of the other (1−w₁) names

—

Live outputs

Asset contribution

—

w₁ × R₁

Rest contribution

—

(1−w₁) × R_rest

Net portfolio return

—

R_p — sum of contributions

Asset impact ratio

—

asset contrib ÷ net return

Decomposition

Asset return (R₁)—

Asset contribution to portfolio—

Rest contribution to portfolio—

Net portfolio return (R_p)—

Sensitivity — portfolio return as a function of weight

Portfolio return vs. observed weight

As the observed weight moves from 0% to 100%, portfolio return interpolates linearly between the rest-of-portfolio return and the observed asset return. The dashed line marks the current weight.

Reading guide

Asset contribution

How much the observed name moves the whole portfolio. A 10% position dropping 30% subtracts 3.0% from R_p.

Asset impact ratio

Share of the net portfolio return that came from this single name. >100% means the rest of the portfolio is offsetting, <0% means rest dominated.

Use cases

Stress-test concentration limits · sanity-check sizing decisions · understand drawdown tolerance before adding to a position.

"This is not advice or a forecast. It is a sanity check. Sliders cannot substitute for the work of building conviction in the underlying business."

— Atlas AM · how we use this tool