Mainstay Medical Announces US$125 Million Equity Financing Transaction

Mainstay Medical Holdings plc today announced an equity financing in which it will receive gross proceeds of US$125 million. Mainstay intends to use the funds to support the company's continued commercial growth of ReActiv8^® Restorative Neurostimulation in the U.S., Europe and Australia, additional post-market clinical studies and research, and general operations.

The financing was co-led by new investors Gilde Healthcare and Viking Global Investors. Key existing investors who participated in the financing include Ally Bridge Group, Sofinnova Partners (Crossover Fund), Fountain Healthcare Partners, and Perceptive Advisors.

"A financing of this magnitude will allow us to accelerate our efforts to revolutionize the treatment of mechanical low back pain through ReActiv8 Restorative Neurostimulation, including by continuing our rapid commercial growth and building on our insurance coverage for ReActiv8," said Jason Hannon, CEO of Mainstay Medical. "We are now strongly capitalized to execute on our corporate objectives. In addition to commercial expansion in our target markets, these objectives include the generation of additional clinical and health economic data to further demonstrate that ReActiv8's purpose-built, restorative approach to the treatment of mechanical chronic low back pain is superior to competitive therapies originally designed for other indications, as well as the continued development and enforcement of our dominant intellectual property portfolio."

"We are excited to lead this financing and to work with Mainstay to continue to unlock the potential of ReActiv8 therapy," said Geoff Pardo, Partner at Gilde Healthcare, who also joins the Mainstay Medical Board of Directors. "Patients with mechanical chronic low back pain have had very limited treatment options, and the restorative mechanism of action offered by ReActiv8 is both unique and very promising."

Two extraordinary general meetings of Mainstay shareholders were held on 23 February 2024 to approve the financing and related matters. At the EGMs, all resolutions were duly passed. The results of the voting on each of the resolutions is available on the Company's website.

About ReActiv8^®

ReActiv8 is an implantable medical device designed to treat adults with intractable chronic low back pain (CLBP) associated with multifidus muscle dysfunction. Multifidus muscle dysfunction may be evidenced by imaging or physiological testing in adults who have failed therapy including pain medications and physical therapy, and who are not candidates for spine surgery. ReActiv8 has received regulatory approval in several geographic areas, and is commercially available in the European Economic Area, Australia, the UK, and the US.

About Mainstay Medical

Mainstay Medical is a medical device company focused on commercializing its innovative implantable Restorative Neurostimulation system, ReActiv8, for people with disabling mechanical CLBP. Mainstay Medical is headquartered in Dublin, Ireland and has subsidiaries operating in Ireland, the United States, Australia, Germany, and the Netherlands.

Further information can be found at www.mainstaymedical.com.

Mainstay Forward-Looking Statements

All statements in this announcement other than statements of historical fact are, or may be deemed to be, forward-looking statements. These forward-looking statements may include, without limitation, statements regarding the company's intentions, beliefs or current expectations concerning, among other things, the company's funding needs, strategies, alternatives and transactions, ability to fund its objectives moving forward, commercial efforts and performance, research studies and results, financial position, product design and development, intellectual property portfolio and its scope, regulatory applications and approvals, and reimbursement arrangements.

Forward-looking statements involve risk and uncertainty and are not guarantees of future performance. Actual results may differ materially from those described in, or suggested by, the forward-looking statements. A number of factors could cause results and developments to differ materially from those expressed or implied by the forward-looking statements herein, including, without limitation, the risks and uncertainties included in the company's Annual Report for the year ended 31 December 2022, which should be read in conjunction with the company's public disclosures (available on the company's website (www.mainstaymedical.com)). The forward-looking statements herein speak only as of the date of this announcement.