Southeastern Q1 2026: Longleaf's Deep-Value Adds

Southeastern Asset Management, the firm behind the Longleaf Partners funds, reported a $2.03B U.S. equity book for the quarter ended March 31, 2026 (Form 13F-HR, accession 0001398344-26-009296, filed 2026-05-15). Southeastern is a classic concentrated deep-value manager, and its Q1 2026 filing shows it doing what value investors do best: buying out-of-favor, idiosyncratic businesses while others look away. The firm added aggressively to timber REIT Rayonier (RYN) (+90%), Fortune Brands (FBIN) (+83%), and toymaker Mattel (MAT) (+49%).

The book is concentrated — 49 positions, with the top five at roughly 42% — and full of the kind of cheap, special-situation names Southeastern is known for: Rayonier, Mattel, Barry Diller's IAC, natural-gas producer CNX Resources (CNX), and grocery chain Albertsons (ACI).

Against the adds, Southeastern trimmed FedEx (FDX) (-31%), Regeneron (REGN) (-21%), and MGM Resorts (MGM) (-18%).

A concentrated deep-value book

Rayonier leads at 10.92%, followed by Mattel at 9.16%, IAC at 7.92%, CNX at 7.61%, and Albertsons at 6.22%. The lineup reflects Southeastern's "price-to-value" discipline — buying businesses trading well below the firm's estimate of intrinsic worth, often with a catalyst or an activist angle.

These are not crowded megacaps. Timber, toys, a holding company, natural gas, and grocery are unglamorous, frequently overlooked corners of the market — exactly where a deep-value manager hunts. With the top five at 42% of the book, Southeastern concentrates capital in its highest-conviction value ideas.

Leaning into the cheapest names

The quarter's adds were decisive. The 90% increase in Rayonier and 83% in Fortune Brands are large moves in a concentrated book, signaling rising conviction in those names, with a 49% add to Mattel and 20% to Albertsons reinforcing the value tilt.

The trims to FedEx, Regeneron, and MGM funded those additions. The pattern is a value manager rotating capital toward its cheapest, most idiosyncratic opportunities — buying timber and toys while trimming a logistics name and a biotech.

What it means for 13F readers

Southeastern offers a window into concentrated deep-value investing far from the megacap crowd. The Rayonier, Fortune Brands, and Mattel adds are the quarter's signals — high-conviction moves into unloved names. Track the firm's quarter-over-quarter holdings on the Southeastern Asset Management filer page.

FAQ

What is Southeastern Asset Management?

Southeastern Asset Management is the concentrated deep-value firm behind the Longleaf Partners funds, known for a "price-to-value" discipline. It reported a $2.03B U.S. equity 13F book for the quarter ended March 31, 2026.

What are Southeastern's largest holdings?

Its five largest positions are Rayonier (10.92%), Mattel (9.16%), IAC (7.92%), CNX Resources (7.61%), and Albertsons (6.22%) — a concentrated, out-of-favor value book.

What did Southeastern buy in Q1 2026?

It added aggressively to Rayonier (+90%), Fortune Brands (+83%), Mattel (+49%), and Albertsons (+20%), while trimming FedEx, Regeneron, and MGM.

What kind of stocks does Southeastern favor?

Cheap, idiosyncratic, often overlooked businesses — timber, toys, holding companies, natural gas, and grocery — bought below the firm's estimate of intrinsic value, frequently with a catalyst.