Company: STBA
Filing Date: 2025-06-23
Form Type: 11-K
Source: 0000719220-25-000040
Chunk: 0

Company: S&T BANCORP INC
Filing Date: 2025-06-23
Form: 11-K
Chunk 0
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### SECURITIES AND EXCHANGE COMMISSION

#### Washington, D.C. 20549

#### Form 11-K
<div align='center'>x ANNUAL REPORT PURSUANT TO SECTION 15 (d) OF THE SECURITIES EXCHANGE ACT OF 1934</div>

#### For the fiscal year ended December 31, 2024

#### OR
<div align='center'>¨ TRANSITION REPORT PURSUANT TO SECTION 15 (d) OF THE SECURITIES EXCHANGE ACT OF 1934</div>

#### For the transition period from

#### to

#### Commission file number 0-12508
<div align='center'>A. Full title of the plan and the address of the plan, if different from that of the issuer named below:</div>

### THRIFT PLAN FOR EMPLOYEES OF S&T BANK
<div align='center'>B. Name of issuer of the securities held pursuant to the plan and the address of its principal executive office:</div>

#### S&T BANCORP, INC.

#### 800 PHILADELPHIA STREET

#### INDIANA, PA 15701

### Financial Statements and Supplemental Schedule

#### Thrift Plan for Employees of S&T Bank
<div align='center'>Years ended December 2024 and 2023

With Report of Independent Registered Public Accounting Firm</div>

#### Thrift Plan for Employees of S&T Bank

### Financial Statements and Supplemental Schedule
<div align='center'>Years ended December 2024 and 2023</div>

#### Contents
| Report of Independent Registered Public Accounting Firm        |     | 1 |     |    |
| Audited Financial Statements                                   |     |   |     |    |
| Statements of Net Assets Available for Benefits                |     | 3 |     |    |
| Statements of Changes in Net Assets Available for Benefits     |     | 4 |     |    |
| Notes to Financial Statements                                  |     | 5 |     |    |
| Schedule H, Line 4(i)-Schedule of Assets (Held at End of Year) |     |   |     | 11 |
| Signatures                                                     |     |   |     | 12 |

<div align='center'>REPORT OF INDEPENDENT REGISTERED PUBLIC ACCOUNTING FIRM</div>

Thrift Plan Committee

S&T Bank

Indiana, Pennsylvania

#### Opinion on the Financial Statements
We have audited the accompanying statements of net assets available for benefits of the