It routinely upgrades its portfolio to create more value for shareholders as it grows bigger. One likely motivation why Buffett's company owns so much Chevron stock is its focus on getting better as it grows bigger.

Investment Clinic is produced by Mischa Frankl-Duval with sound design and mixing by Breen Turner, Sam Giovinco and Joe Salcedo. Manuela Saragosa is the show’s executive producer and Cheryl Brumley is the FT’s global head of audio.

Warren Buffett is undoubtedly one of the greatest investors of all time. Part of the widespread positive view of Buffett has to do with the Oracle of Omaha’s investment philosophy, which has stood the test of time.