 Tom Gayner Trades, Portfolio, chief investment officer of Markel Corp. MKL , Financial, disclosed this week that his firms top five trades during the first quarter included a new buy in Regeneron Pharmaceuticals Inc. REGN , Financial, position boosts in Equifax Inc. EFX , Financial and International Flavors Fragrances Inc. IFF , Financial and reductions in the Microchip Technology Inc. MCHP , Financial and O-I Glass Inc. OI , Financial holdings. 