X0306 4 2020-05-29 0001025835 ENTERPRISE FINANCIAL SERVICES CORP EFSC 0001731826 IANNACONE NICOLE M 150 N. MERAMEC CLAYTON MO 63105 1 EVP, Chief Risk Officer Common Stock 2020-05-29 5 J 0 E 779 24.96 A 3215 D Restricted Share Units Common Stock 286 286 D Restricted Share Units Common Stock 391 391 D Restricted Share Units Common Stock 540 540 D The reporting person is voluntarily reporting the acquisition of shares of the Issuer's common stock pursuant to the Issuer's 2018 Employee Stock Purchase Plan ("ESPP") for the ESPP purchase period of December 1, 2019 through May 31, 2020. This transaction is exempt under Section 16b-3(c). In accordance with the terms of the ESPP, the reported shares were acquired based on 85% of the closing price of the Issuer's common stock on May 29, 2020. The RSU's were granted pursuant to the Company's 2018 Stock Incentive Plan. Each RSU represents the right to receive one share of Common Stock, subject to adjustment as provided in the Grant Agreement. The RSU's vest 100% in the first quarter of 2021, subject to continued employment by the reporting person. The RSU's vest 100% in the first quarter of 2022, subject to continued employment by the reporting person. The RSU's vest 100% in the first quarter of 2023, subject to continued employment by the reporting person. /s/ Nicole M. Iannacone 2020-06-04