What can we learn from studying the investments of great investors, and how much of their success comes down to doing the work that others overlook?

Those questions sit at the heart of Tim Isgro’s The Owner’s Memo, where he reconstructs investments made by investors such as Li Lu, Eddie Lampert, and Mohnish Pabrai.

Rather than simply looking back at a successful stock and explaining why it went up, Tim digs into the original filings, historical reports, and information available at the time to recreate the uncertainty, research, and judgment behind the investment decision. His goal is to make these case studies useful for investors facing their own decisions today.

The event featured five companies across different industries: $ISEYF, a manufacturer of precision timing components; $CVALF, a medical technology company; $CDTI, a catalyst engineering and coating technology provider; $DDOSF, a cybersecurity company; and $CLIR, an industrial combustion technology developer. Soueidan also introduced GeoInvesting analyst Diego La Torre who came with a pitch and guest moderators Ben Brostoff and Jev, explaining that the sessions would focus on business fundamentals, growth opportunities, financial sustainability, and direct discussions with management.

In our previous Skull Sessions interview with Sidecar Investor, we asked him who he’d like to see us interview next. His answer was Scott Felsenthal, who he described as having a “unique combination of experience running private companies and investing in public businesses.”

Scott has spent years on the operating side of business, including more than a decade at Whitmor, a fourth-generation family business where he eventually became CEO. He knows what it’s like to make the decisions investors analyze from the outside: allocating capital, managing people, dealing with customers and lenders, making acquisitions, and navigating difficult periods.

I recently came across Matheus Lonning while perusing “X” at 1 AM, sitting and having a few drinks at the El Camino Restaurant on Las Olas Boulevard in downtown Fort Lauderdale. El Camino is Spanish for “the path”. Like many young investors these days, Matheus’ path reminds me of the one I took when I was fortunate enough to discover the world of small and microcap investing and the ROI that came from hard work. Matheus has built a following through his Substack and X by digging into obscure microcaps, reading filings, talking directly with management teams..

This week, Sidecar Investor ( SidecarCap on “X”) brings an interesting perspective to our Investor Notebook Q&A conversations. He is a private investor, but his background spans trading, fund management, institutional asset management and wealth management, and he is also runs Sidecar Partners, an investment firm built around “partnering with exceptional business operators for the long run.”

So, for the second edition, we’re featuring Sergi Mascaro, an investor who has been involved in the markets since he was a teenager and has developed a differentiated approach to finding small companies, early.

Over the last several weeks, I’ve been doing a good deal of communicating with Sergi. So many of his X posts talk about stocks I own, or are being covered at the Microcap Investing Cliff Notes Substack and GeoInvesting, like Optical Cable Corporation (NASDAQ:OCC) and Sci Engineered Materials, Inc. (OTCQB:SCIA).

Sergi has built his process around finding companies going through early inflection points. His background in physics and CFA studies gives him a pretty analytical mindset, yet he’s not interested in making investing complicated. He talks a lot about knowing companies for years and how that helps him to move quickly when the facts change.

Tim Heitman is a great person to kick off this format, who I consider a friend, as much as I do a colleague. Tim has been part of the GEO Investing community for some time and has joined us for Video Skull Session interviews in the past, so many of you may already be familiar with him.

This time, rather than doing another video conversation, I wanted to give Tim the opportunity to go deeper on some topics and experiences that have shaped his approach.

He’s been investing for decades and has developed a thoughtful framework around fundamental research, what he calls “time arbitrage” and investing in smaller companies. He loves talking stocks and is great at breaking down businesses and building models. We had our original Skull Session with Tim back in August 2023, before we launched this Substack. You can watch the video at Geoinvesting along with our take on the conversation here or you can watch it on this Substack, here, where we just published the video yesterday.

Day Two of Summer 2026 Virtual Conference shifted toward investor pitches and idea sharing. Gurkirat Singh, Aurelion Research, Multibagger Mike, Ben Brostoff, Lee Roach each presented an investment idea. We carried one final investor pitch into Friday morning. After hearing this company present during the conference, I wanted additional time to revisit the notes, continue the research and develop the investment case further before sharing it.