The strongest evidence that impact investing can beat the market comes from Schroders and Oxford Saïd Business School. In their study, 8 of 10 randomly built impact portfolios outperformed the MSCI ACWI IMI between 2010 and 2023. Two other sources point the same way: the Corporate Knights Clean200 and the Global Impact Investing Network (GIIN) survey of impact investors. Fund data from Morgan Stanley is more mixed. Sustainable funds trailed traditional funds in two of the last four half-years.
Each source measures something different. That difference decides how much weight each result deserves. For the broader case, see Ziggma's guide to impact investing.
Schroders and Oxford Saïd Business School found that impact portfolios beat the global stock market in most of the scenarios they tested. The researchers started with 257 listed companies that create positive impact. They built 10 random portfolios of 40 stocks each from that group. Eight of the 10 portfolios outperformed the MSCI ACWI IMI between 2010 and 2023.
The Schroders study is the only source in this article that tests impact companies directly. It's also a backtest. The portfolios were built after the fact, and past results don't guarantee future returns.
The Corporate Knights Clean200 returned 282.9% between its launch on July 1, 2016 and January 26, 2026. The MSCI ACWI returned 221.3% over the same period. The MSCI ACWI/Energy Index of fossil fuel companies returned 111.0%.
Corporate Knights and As You Sow publish the Clean200 every year. The 2026 edition chose 200 public companies out of 8,229, ranked by sustainable revenue. Clean200 companies earn an average of 53.7% of their revenue from sustainable activities. Companies in the MSCI ACWI earn 16.7%.
The Clean200 measures what companies sell. It doesn't score labor practices, governance or controversies. A full impact assessment covers those too. Ziggma's best climate stocks list applies both lenses.
Sustainable funds have beaten traditional funds over the long run, but they haven't won every period. The Morgan Stanley Institute for Sustainable Investing compares both groups every six months in its Sustainable Reality report, using Morningstar data.
Morgan Stanley applies median fund returns to a hypothetical $100 invested in December 2018. By mid-2026, that $100 grew to $171 in sustainable funds and $159 in traditional funds.
Morgan Stanley's data covers every fund that Morningstar classifies as sustainable. That category includes ESG funds, sustainability-themed funds and impact funds. ESG criteria measure risks to a company, not the company's effect on the world. The Morgan Stanley data shows that sustainability-labeled funds haven't cost investors returns. It's weaker evidence about impact investing itself.
Nine in 10 impact investors met or exceeded their financial expectations, according to the Global Impact Investing Network's State of the Market 2025 report. The survey also found that 88% met or exceeded their impact goals. The GIIN surveyed 429 organizations in 54 countries.
Impact assets among those investors grew 21% a year over six years. Their total assets grew 5% a year.
The GIIN results come with two limits. Investors measured returns against their own expectations, not against a market benchmark. And most respondents invest directly in private companies, projects and real assets, so the survey says little about public stocks. Ziggma explains how impact works in listed markets in its guide to public market impact investing.
Sustainable funds lagged traditional funds in the second half of 2024 and the second half of 2025, according to Morgan Stanley. In 2024, only 42% of US sustainable funds finished in the top half of their Morningstar category. Morningstar cited high interest rates, which hurt clean energy stocks and other growth companies.
Those setbacks were short-term. Over longer horizons, the evidence points to outperformance. Sustainable funds turned $100 into $171 between December 2018 and mid-2026, vs. $159 for traditional funds. The Clean200 beat the MSCI ACWI by 61.6 percentage points over nearly a decade. And 8 of 10 Schroders impact portfolios outperformed over the 14 years between 2010 and 2023.
Impact companies outperformed in the Schroders and Oxford Saïd study because they run differently from the average listed company. The researchers compared the financial profiles of 257 impact companies against traditional benchmarks. They controlled for size, value, momentum, profitability and investment, the standard factors that explain most stock returns. The impact portfolios still showed statistically significant alpha. Schroders traces that alpha to six characteristics.
The more of a company's revenue comes from products with positive impact, the stronger its financial performance tended to be. Schroders calls this impact materiality. A company leading the low-carbon transition or expanding financial inclusion scores high on it. A company with a small green side business scores low. This is the study's central finding: impact pays when it's the business itself, not a side project.
Impact companies earned higher operating margins than their benchmarks. They kept more profit from each dollar of revenue before interest and taxes. Schroders reads this as a sign of stronger business fundamentals. Higher margins also leave more room to absorb cost shocks and fund growth.
Impact companies grew their headcount faster. Schroders links this to active expansion. Companies hire ahead of demand when they expect their markets to grow, and the markets these companies serve, such as clean energy, healthcare and financial inclusion, have been growing.
Impact companies held less cash relative to their total assets. They also raised equity and debt more often than their benchmarks. Schroders attributes both patterns to a growth orientation. These companies reinvest capital in expansion instead of leaving it idle on the balance sheet.
A larger share of impact companies' assets was tangible, such as plants, equipment and infrastructure. Schroders ties this to their sectors, including renewable energy and infrastructure, and to early-stage growth. Younger companies have usually made fewer acquisitions, so less of their balance sheet is goodwill.
Investors paid more for impact companies. They traded at lower earnings-to-price and free-cash-flow-to-price ratios, which means higher price-to-earnings multiples. Schroders notes this matches the profile of high-growth companies. Higher multiples also carry risk: when interest rates rise, growth stocks tend to fall further, as they did in 2024.
The outperformance didn't come from taking more risk. Schroders found that the impact portfolios had lower volatility, smaller drawdowns and milder negative skewness than conventional indices. Put simply, their losses were smaller and less extreme.
Those traits describe efficient, growing businesses. Not every impact company has them. Screening for financial quality separates the ones that do from the ones that don't.
Impact investing is an overlooked source of alpha for self-directed investors. In the strongest study available, Schroders and Oxford Saïd Business School found that 8 of 10 random impact portfolios beat the MSCI ACWI IMI between 2010 and 2023. The Corporate Knights Clean200 beat the MSCI ACWI by 61.6 percentage points between July 2016 and January 2026. The assumption that impact costs returns doesn't survive that record.
The drivers of that outperformance are basic business sense. Companies with higher operating margins keep more of every dollar they earn. Companies that put their cash to work grow faster than companies that sit on it. Companies that keep hiring are expanding to meet demand. And companies working on decarbonization, water and healthcare sell into needs that won't go away.
Impact investors don't have to trade returns for their values. They have to own the right companies, which means screening for impact and financial quality together.
Start with what you already own. Ziggma's Impact X-Ray scores every holding across your linked brokerage accounts on Climate Action, Resource Use, Fair Labor and Accountability.
Then add a quality filter. The Ziggma Stock Score rates companies 0–100 on growth, valuation, profitability and financial health. Screening on both the Ziggma Impact Score and the Ziggma Stock Score removes impact companies with weak fundamentals.
Ziggma's impact model portfolios use this approach. Better Future owns companies with strong Ziggma Stock Scores and strong Ziggma Impact Scores. Climate Opportunity and Solutions targets companies building the technology and infrastructure for a low-carbon economy. Growth, Impact, Momentum adds a price momentum filter. For individual ideas, see Ziggma's best sustainable stocks.
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