The remainder of this cover page shall be filled out for a reporting person’s initial filing on this form with respect to the subject class of securities, and for any subsequent amendment containing information which would alter the disclosures provided in a prior cover page.

Names of Reporting Persons

I.R.S. Identification No. of Above Persons (Entities Only)

The Kiser 2012 Gift Trust

Check the Appropriate Box if a Member of a Group (See Instructions)

(a)  ☐        (b)  ☐

SEC Use Only

Citizenship or Place of Organization

South Carolina

Number of

Shares

Beneficially

Owned by

Each

Reporting

Person

With

Sole Voting Power*

948,157

Shared Voting Power*

0

Sole Dispositive Power*

948,157

Shared Dispositive Power*

0

Aggregate Amount Beneficially Owned by Each Reporting Person*

2,013,890

Check if the Aggregate Amount in Row (9) Excludes Certain Shares (See Instructions)  ☐

Percent of Class Represented by Amount in Row (9)*

5.46%

Type of Reporting Person (See Instructions)

OO

See Item 4 below.

Names of Reporting Persons

I.R.S. Identification No. of Above Persons (Entities Only)

The John Daniel Kiser Revocable Trust U/A/D July 27, 2011

Check the Appropriate Box if a Member of a Group (See Instructions)

(a)  ☐        (b)  ☐

SEC Use Only

Citizenship or Place of Organization

Florida

Number of

Shares

Beneficially

Owned by

Each

Reporting

Person

With

Sole Voting Power*

565,733

Shared Voting Power*

0

Sole Dispositive Power*

565,733

Shared Dispositive Power*

0

Aggregate Amount Beneficially Owned by Each Reporting Person*

2,013,890

Check if the Aggregate Amount in Row (9) Excludes Certain Shares (See Instructions)  ☐

Percent of Class Represented by Amount in Row (9)*

5.46%

Type of Reporting Person (See Instructions)

OO

See Item 4 below.

Names of Reporting Persons

I.R.S. Identification No. of Above Persons (Entities Only)

The Kiser 2019 Grantor Retained Annuity Trust

Check the Appropriate Box if a Member of a Group (See Instructions)

(a)  ☐        (b)  ☐

SEC Use Only

Citizenship or Place of Organization

Florida

Number of

Shares

Beneficially

Owned by

Each

Reporting

Person

With

Sole Voting Power*

340,987

Shared Voting Power*

0

Sole Dispositive Power*

340,987

Shared Dispositive Power*

0

Aggregate Amount Beneficially Owned by Each Reporting Person*

2,013,890

Check if the Aggregate Amount in Row (9) Excludes Certain Shares (See Instructions)  ☐

Percent of Class Represented by Amount in Row (9)*

5.46%

Type of Reporting Person (See Instructions)

OO

See Item 4 below.

Names of Reporting Persons

I.R.S. Identification No. of Above Persons (Entities Only)

The Kiser 2018 Grantor Retained Annuity Trust

Check the Appropriate Box if a Member of a Group (See Instructions)

(a)  ☐        (b)  ☐

SEC Use Only

Citizenship or Place of Organization

Florida

Number of

Shares

Beneficially

Owned by

Each

Reporting

Person

With

Sole Voting Power*

159,013

Shared Voting Power*

0

Sole Dispositive Power*

159,013

Shared Dispositive Power*

0

Aggregate Amount Beneficially Owned by Each Reporting Person*

2,013,890

Check if the Aggregate Amount in Row (9) Excludes Certain Shares (See Instructions)  ☐

Percent of Class Represented by Amount in Row (9)*

5.46%

Type of Reporting Person (See Instructions)

OO

See Item 4 below.

Name of Issuer

REGENXBIO Inc.

Address of Issuer’s Principal Executive Offices

9600 Blackwell Road, Suite 210

Rockville, Maryland 20850

Name of Person(s) Filing

The Kiser 2012 Gift Trust (the “Kiser Gift Trust”) is a South Carolina trust, for which Allan M. Fox serves as co-trustee, which was established for the benefit of John Daniel Kiser’s family. The John Daniel Kiser Revocable Trust U/A/D July 27, 2011 (the “Kiser Revocable Trust”) is a Florida trust, for which Mr. Kiser serves as trustee, which was established for the benefit of Mr. Kiser’s family. Each of The Kiser 2018 Grantor Retained Annuity Trust (the “Kiser 2018 Retained Annuity Trust”) and The Kiser 2019 Grantor Retained Annuity Trust (the “Kiser 2019 Retained Annuity Trust”) is a Florida trust, for which Ellen G. Kiser, the wife of Mr. Kiser, serves as trustee, which was established for the benefit of Ms. Kiser’s family.

Address of Principal Business Office or, if none, Residence

1701 Pennsylvania Avenue, NW, Suite 900

Washington, DC 20006

Citizenship

Florida (the Kiser Revocable Trust, the Kiser 2018 Retained Annuity Trust and the Kiser 2019 Retained Annuity Trust) and South Carolina (the Kiser Gift Trust)

Title of Class of Securities

Common Stock, par value $0.0001 per share

CUSIP Number

75901B107

Item 3.   If this statement is filed pursuant to §§240.13d-1(b) or 240.13d-2(b) or (c), check whether the person filing is a:

Not applicable.

Item 4.   Ownership

(i) Sole power to vote or to direct the vote:

The Kiser Gift Trust

The Kiser Revocable Trust

The Kiser 2019 Retained Annuity Trust

The Kiser 2018 Retained Annuity Trust

(ii) Shared power to vote or to direct the vote:

(iii) Sole power to dispose or to direct the disposition of:

The Kiser Gift Trust

The Kiser Revocable Trust

The Kiser 2019 Retained Annuity Trust

The Kiser 2018 Retained Annuity Trust

(iv) Shared power to dispose or to direct the disposition of:

Based upon 36,874,282 shares of common stock of the Issuer outstanding as of November 1, 2019, as reported in the Issuer’s Quarterly Report on Form 10-Q filed with the Securities and Exchange Commission on November 5, 2019.

Ownership of Five Percent or Less of a Class

Ownership of More than Five Percent on Behalf of Another Person

Identification and Classification of the Subsidiary Which Acquired the Security Being Reported on By the Parent Holding Company or Control Person

Identification and Classification of Members of the Group

Notice of Dissolution of Group

Certification

each of them is individually eligible to use the Amendment No. 2 on Schedule 13G to which this Exhibit is attached, and such Amendment No. 2 to Schedule 13G is filed on behalf of each of them; and

each of them is responsible for the timely filing of such Amendment No. 2 to Schedule 13G and any subsequent amendments thereto, and for the completeness and accuracy of the information concerning such person contained therein; but none of them is responsible for the completeness or accuracy of the information concerning the other persons making the filing, unless such person knows or has reason to believe that such information is inaccurate.