This communication does not constitute an offer to sell or a solicitation of an offer to sell or a solicitation of an offer to buy any securities or a solicitation of any vote or approval, nor shall there be any sale of securities in any jurisdiction in which such offer, solicitation or sale would be unlawful prior to registration or qualification under the securities laws of any such jurisdiction.  

ADDITIONAL INFORMATION AND WHERE TO FIND IT

WGL Holdings, Inc. ("WGL") has filed with the U.S. Securities and Exchange Commission (the "SEC") and mailed to its shareholders a proxy statement in connection with the proposed merger transaction. THE INVESTORS AND SECURITY HOLDERS OF WGL ARE URGED TO READ THE PROXY STATEMENT AND ANY OTHER RELEVANT DOCUMENTS WHEN THEY BECOME AVAILABLE, BECAUSE THEY WILL CONTAIN IMPORTANT INFORMATION about AltaGas, WGL and the proposed merger transaction. Investors and security holders will be able to obtain these materials (when they are available) and other documents filed with the SEC free of charge at the SEC's website , www.sec.gov. In addition, a copy of WGL's proxy statement (when it becomes available) may be obtained free of charge upon request by contacting WGL Holdings, Inc., Corporate Secretary, 101 Constitution Avenue N.W., Washington, District of Columbia, 20080. WGL's filings with the SEC are also available on WGL's website at: http://wglholdings.com/sec.cfm Investors and security holders may also read and copy any reports, statements and other information filed by WGL with the SEC , at the SEC public reference room at 100 F Street, N.E., Washington, D.C. 20549. Please call the SEC at 1-800-SEC-0330  or visit the SEC's website for further information on its public reference room.

PARTICIPANTS IN THE SOLICITATION

AltaGas, WGL and certain of their respective directors, executive officers and other persons may be deemed to be participants in the solicitation of proxies in respect of the proposed merger transaction. Information regarding AltaGas' directors and executive officers is available in AltaGas' Management Information Circular, filed on March 17, 2016 (in English and French) with the Canadian Securities Administrators (the "CSA") and in AltaGas' Annual Information Form, filed on March 23, 2016 (in English) and March 24, 2016 (in French) with the CSA, each of which are available at: www.sedar.com. Information regarding WGL's directors and executive officers is available in WGL's proxy statement filed with the SEC on December 23, 2016 in connection with its 2017 annual meeting of shareholders, and its Annual Report on Form 10-K for the fiscal year ended September 30, 2016, each of which may be obtained from the sources indicated in Additional Information and Where to Find It. Other information regarding persons who may be deemed participants in the proxy solicitation and a description of their direct and indirect interests (which may be different than those of WGL's investors and security holders), by security holdings or otherwise, will be contained in the proxy statement and other relevant materials filed or to be filed with the SEC when they become available.

LINKS TO THIRD PARTY WEBSITES

Neither AltaGas or WGL Holdings control any third party website and are therefore not responsible for the content of any linked website or any link contained in a linked website. These links have been provided solely as a convenience for visitors of this website and do not constitute an endorsement by AltaGas or WGL Holdings of the content of such third party websites. With respect to links to third party media websites, such material accessed through third party links on this website may include the views or recommendations of third parties, which do not necessarily reflect the views of AltaGas or WGL Holdings, and do not constitute an endorsement by AltaGas or WGL Holdings or indicate their commitment to a particular course of action.  The links to such third party media coverage comprise only a selection of total available third party media coverage of AltaGas and WGL Holdings available; such selected links do not provide a comprehensive set of available media coverage and may not provide a full or complete picture of the views or information available in the total third party media coverage of AltaGas or WGL Holdings. The inclusion of any link does not imply that the linked website or information contained therein has been investigated or verified by AltaGas or WGL Holdings.