Positive screening identifies companies producing measurable positive outcomes, so an investor can weight a portfolio toward them. It demands a floor on real-world impact rather than a limit on harm. Most values-driven portfolios stop at exclusion. Negative screening answers what your values prevent you from owning. Positive screening answers what they point you toward owning.
Ziggma carries an Impact Score for every security, rating it 0 to 100 on the outcomes it produces in the world, across 600+ metrics and 80 topic-level scores. An investor can screen on the score itself, or on the metrics underneath it: carbon emissions, water use, employee ratings. Ecolab (ECL), First Solar (FSLR), and Amalgamated Financial (AMAL) are recurring examples in positively screened public portfolios.
Positive screening selects holdings by the positive real-world outcomes a company measurably produces. An investor sets a level on something countable — emissions falling by a given percentage, a share of waste recycled, a workforce rating — and keeps the companies that clear it. Hannon Armstrong (HASI) has reduced its emissions per dollar of revenue by 21%, scores 67 on Sustainable Water Use, and holds an employee rating of 3.35 out of 5. Set the floor for emissions intensity reduction at 15% and HASI clears it. Set it at 25% and it doesn’t.
An exclusion asks what a company is. A positive screen asks what it measurably does. Alcoa (AA) produces aluminum. Smelting is among the most energy-intensive industrial processes there is, so Alcoa’s carbon intensity of 3918 tCO₂e per $M revenue is high by the nature of the activity, and many funds exclude the sector on that basis alone. The same company draws 86% of its energy from renewables, scores 91 on Sustainable Resource Use, and holds an Impact Score of 81, ranking it first for impact among steel works companies. A sector-level exclusion removes Alcoa. A screen on renewable energy keeps it. This is what best-in-class screening means: holding the leaders within a sector rather than excluding the sector.
The second advantage is positive real-world impact. Exclusion withholds capital from harm. Positive screening directs it toward companies measurably producing good. Both work through the same mechanism — the cost of capital a company faces — in opposite directions, and that mechanism is set out on the public-market impact investing hub.
Excluding a category requires knowing what a company sells. Selecting on outcomes requires knowing what a company measurably does: how fast its emissions are falling, what share of its waste is recycled, how its workers rate it, what it has been fined for. That data has only recently become available at security level to retail investors. ACA Ethos assesses it across 600+ metrics and 80 topic-level scores, and Ziggma surfaces it per holding.
Exclusion is the older method by two and a half centuries, and it began with religious groups rather than financial ones — the Quakers barring members from the slave trade in 1758, John Wesley setting out the tenets of social investing in 1760, the Pioneer Fund carrying those screens into public markets in 1928. That inheritance explains the limit. Exclusion was built to keep a congregation’s money out of something, not to decide what it should go into instead. Most still stop where the Quakers stopped — at the boundary. Positive screening is what happens past it.
Positive screening measures emissions, water use, and labor practices company by company. The results surface companies across unrelated sectors.
Amalgamated Financial (AMAL) is the only publicly listed US bank certified as a B Corporation, and has been since 2017. The certification is an independent assessment of the whole business, not a rating of financial risk.
Ecolab (ECL) ranks first for impact among consumer goods companies, and its Fair Labor Practices sub-score is 52. A CEO-to-median worker pay ratio of 327:1 scores 6 out of 100. The overall rating does not hide that, because every sub-score is reported alongside it. An investor screening on labor practices would exclude ECL on the same data that makes it a leader on climate and resource use.
Ziggma’s Impact filter theme carries two kinds of parameter. Raw metrics, each in its own unit. And scores, each 0–100.
A metric answers one question exactly. A score answers a broader one approximately.
The Impact Score is a 0–100 composite across Climate Action, Sustainable Resource Use, Fair Labor Practices, and Accountability. How it is built, and how ACA Ethos assesses each company, is set out in Ziggma’s impact data methodology.
It is useful as a second read: a company can score well on the metric you screened for and poorly on everything you didn’t. NVIDIA (NVDA) scores 100 on Sustainable Resource Use and 88 on Climate Action, with 100% of its energy from renewables and carbon intensity down 31%. Its Accountability sub-score is 33, and Peace & Justice within it scores 16. A screen on emissions alone would never surface that.
It is not an ESG rating. MSCI and Sustainalytics measure a company’s exposure to financially material risk — risk to the investor. The Impact Score measures outcomes in the world. The difference is covered in ESG vs. impact investing.
