Company: AWK
Filing Date: 2025-12-17
Form Type: S-4
Source: 0001193125-25-321389
Chunk: 163

Company: American Water Works Company, Inc.
Filing Date: 2025-12-17
Form: S-4
Chunk 163
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 officers are:

| • |     | Bradley J. Palmer, Vice President, Chief Accounting Officer |

105

Robert A. Rubin, Essential’s former Chief Accounting Officer who retired on July 31, 2025, does not have any interests in the merger, and therefore is not included in the disclosures below. For purposes of this disclosure, Essential’s non-employeedirectors are Elizabeth B. Amato, Christopher L. Bruner, David A. Ciesinski, Daniel J. Hilferty, W. Bryan Lewis, and Tamara Linde. Certain Assumptions Except as otherwise specifically noted, for purposes of quantifying the potential payments and benefits described in this section, the following assumptions were used:

| • |     | each of Essential’s executive officers will experience a termination without “cause” or for                                     
 “good reason” under his or her change in control agreement or employment agreement, as applicable, and equity award agreements; |

| • |     | the relevant price per share of Essential common stock is $39.63 (the implied value of the merger consideration                                                                                                        
 based on the average closing market price of Essential common stock over the first five business days following the first public announcement of the merger on October 26, 2025, as calculated pursuant to SEC rules); |

| • |     | all cash bonus amounts are calculated assuming target performance; |

| • |     | performance goals applicable to unvested Essential PSUs are deemed achieved at the target level of performance; |

| • |     | the potential payments and benefits described in this section are not subject to a “cutback” to avoid 
 the “golden parachute” excise tax that may be imposed under Section 4999 of the Code;                 |

| • |     | executive officers’ salary and total eligible target cash bonus levels are as in effect as of the date of 
 this joint proxy statement/prospectus;                                                                    |

| • |     | amounts included herein do not take into account any interim compensation increases; and |

The amounts indicated below are estimates based on multiple assumptions that may or may not actually occur or be accurate on the relevant date, including the assumptions described above, and do not reflect certain compensation actions that may occur before completion of the merger. Treatment of Essential Outstanding Equity Awards Essential Stock Options Each Essential stock option that is outstanding immediately prior to the effective time (including each Essential stock option held by an executive officer) will, as of the effective time, whether vested or unvested, be assumed and converted