# EDGAR Filing Document

**Accession Number:** 0001745742
**File Stem:** 0001745742-26-000001
**Filing Date:** 2026-3
**Character Count:** 2411
**Document Hash:** d323642c34d92da7e4839817bf75747b
**Contains OCR:** False
**Source Format:** 

## Filing Content

## Filing Summary
**0001745742-26-000001.hdr.sgml**: 20260309

**ACCESSION NUMBER**: 0001745742-26-000001

**CONFORMED SUBMISSION TYPE**: X-17A-5

**PUBLIC DOCUMENT COUNT**: 2

**CONFORMED PERIOD OF REPORT**: 20251231

**FILED AS OF DATE**: 20260309

**DATE AS OF CHANGE**: 20260309

**EFFECTIVENESS DATE**: 20260309

**PERIOD START**: 20250101

**FILER**: 

**COMPANY DATA:**
- **COMPANY CONFORMED NAME:** MOUNTAINSIDE SECURITIES LLC
- **CENTRAL INDEX KEY:** 0001745742

**ORGANIZATION NAME:**
- **EIN:** 830857697
- **STATE OF INCORPORATION:** DE
- **FISCAL YEAR END:** 1231

**FILING VALUES:**
- **FORM TYPE:** X-17A-5
- **SEC ACT:** 1934 Act
- **SEC FILE NUMBER:** 008-70157
- **FILM NUMBER:** 26734728

**BUSINESS ADDRESS:**
- **STREET 1:** 450 SPRINGFIELD AVENUE,
- **STREET 2:** SUITE 201
- **CITY:** SUMMIT
- **STATE:** NJ
- **ZIP:** 07901
- **BUSINESS PHONE:** 9084181628

**MAIL ADDRESS:**
- **STREET 1:** 450 SPRINGFIELD AVENUE,
- **STREET 2:** SUITE 201
- **CITY:** SUMMIT
- **STATE:** NJ
- **ZIP:** 07901

### Attached PDF Documents

**Attachment 1:** `MountainsidePublic2025.pdf`

_No text found in this document._

### UNITED STATES SECURITIES AND EXCHANGE COMMISSION
**Washington, D.C. 20549**

## FORM X-17A-5

### ANNUAL AUDITED REPORT

### Filer Information

**Filer CIK:** 0001745742

**Filer CCC:** XXXXXXXX

**Is this a LIVE or TEST filing?:** LIVE

**Would you like a Return Copy?:** No

### Submission Information

**Report Period Begin Date:** 01-01-2025

**Report Period End Date:** 12-31-2025

**Type of Registrant:** Broker-dealer

**Any material weaknesses identified?:** No

### Registrant Identification

**Name of Broker-Dealer:** MOUNTAINSIDE SECURITIES LLC

**Business Address:** 450 SPRINGFIELD AVENUE,, SUITE 201, SUMMIT, NJ, 07901

**Contact Person:** Ryan Posner

**Contact Phone:** 908-277-2500

### Independent Public Accountant Identification

**Accountant Name:** Sanville & Company, LLC

**Accountant Address:** 325 North Saint Paul St., Suite 3100, Dallas, TX, 75201

**Accountant Type:** Certified Public Accountant

### OATH OR AFFIRMATION

I, **Ryan Posner**, swear (or affirm) that, to the best of my knowledge and belief, the accompanying financial statements and supporting schedules pertaining to the firm of **MOUNTAINSIDE SECURITIES LLC**, as of **12-31-2025**, are true and correct.

**Signature:** Ryan Posner

**Title:** Member

**Notarized:** Yes