Adapted from Stock Market Maestros: The winning habits, strategies, and mindsets of the world’s best investors, which will be published by Harriman House in March 2026 (Preorder now).
By Lee Freeman-Shor and Clare Flynn Levy
Lee Freeman-Shor is the author of the international bestseller, The Art of Execution: How the world’s best investors get it wrong and still make millions, named by Investing By The Books as one of the “Top 20 Investment Books Ever.” Before becoming a writer, the Citywire 1000 report recognized Lee as one of the world’s top fund managers. His flagship fund received a Gold rating from S&P Capital IQ and the top (AAA) rating by Citywire.
Clare Flynn Levy is CEO & Founder of Essentia Analytics. Prior to setting up Essentia, she spent ten years as a fund manager, in both active equity (running over $1B of pension funds for Deutsche Asset Management), and hedge (as founder and CIO of Avocet Capital Management, a specialist tech fund manager).
When John Barr was a teenager outside Chicago, he spent his summers unloading boxcars of lumber in sweltering heat. After dropping a load of timber in the middle of the road, a co-worker suggested he might be better suited to the office than the yard. That small nudge changed everything.
Barr didn’t follow the family lumber business. Instead, he cultivated an entrepreneurial streak that led him into technology start-ups in the 1980s, through IPOs, acquisitions, and even hostile takeovers. This frontline experience—watching young companies struggle, adapt, and sometimes thrive—would later define his edge as an investor.
His big break came during the defense industry recession of the early 1990s, when a redundancy forced him to pivot. He landed a role as a sell-side analyst at Needham & Company, later moving to Robertson Stephens, where he spearheaded coverage of the era’s top-performing tech IPOs. By 2009, he was back at Needham, this time managing money.
Today, Barr runs nearly $1 billion in small and mid-cap equities. His Needham Aggressive Growth Fund has won multiple performance awards, but he earned his place among the Stock Market Maestros through clear evidence of investment skill:
Though John’s picks only outperform the index 49% of the time, his winners make nearly three times as much as his losers lose: a payoff ratio of 288%. For professional and personal investors alike, it’s proof that success doesn’t come from being right most of the time, but from structuring your process so that when you are right, it counts.
In Stock Market Maestros, meet twelve investors whose extraordinary skill differentiates them in a crowded field. Pre-order now.
John’s philosophy is rooted in a simple but powerful idea: markets are inefficient beyond an 18-24 month horizon. That’s where he hunts for what he calls “Hidden Compounders”: small, overlooked companies quietly building the products, services, and technologies of tomorrow.
Rather than bet big upfront, Barr starts small – often just 0.1% of his portfolio – and scales in as companies hit milestones. This discipline means his losers barely dent the fund, but his winners have room to grow into giants. Some of his biggest successes, like semiconductor equipment maker Nova Ltd, have returned 100× since his first purchase.
Barr calls it planting acorns and patiently waiting for them to grow into mighty oaks. Sometimes, he admits, the seedlings don’t make it – but those that do make all the difference.
John’s way of investing – part vision, part discipline, part resilience – is what Stock Market Maestros captures. Through in-depth conversations with twelve of the world’s most skilled investors – including case studies on specific positions and decisions – the book reveals how masters like John Barr turn ordinary stock ideas into extraordinary long-term outcomes.
If you want to learn how to think, act, and execute like a true Maestro, pre-order your copy of Stock Market Maestros today.
Stock Market Maestros: The winning habits, strategies, and mindsets of the world’s best investors is published by Harriman House and goes on sale in March 2026. Reserve your copy now!
About Essentia Analytics
Essentia Analytics is the leading provider of behavioral data analytics services to professional investors and allocators of capital. Led by a team of experts in investment management, technology and behavioral science, Essentia combines next-generation decision attribution analytics technology with human coaching to help both equity fund managers and allocators identify investment skill and bias — and capture performance that was previously being lost to decision-making deficiencies.
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