1stdibs.com, Inc.

Adjusted EBITDA and Adjusted EBITDA Margin

In this press release, we provide Adjusted EBITDA, a non-GAAP financial measure that represents our net loss adjusted to exclude: (1) depreciation and amortization; (2) stock-based compensation expense; (3) other income, net; and (4) strategic alternative expenses. We also provide Adjusted EBITDA Margin, a non-GAAP financial measure that presents Adjusted EBITDA divided by net revenue. Below is a reconciliation of net loss, the most directly comparable GAAP financial measure, to Adjusted EBITDA.

We have included Adjusted EBITDA and Adjusted EBITDA Margin, which are non-GAAP financial measures, because they are key measures used by our management team to help us to assess our operating performance and the operating leverage in our business. We also use these measures to analyze our financial results, establish budgets and operational goals for managing our business, and make strategic decisions. We believe that Adjusted EBITDA and Adjusted EBITDA Margin help identify underlying trends in our business that could otherwise be masked by the effect of the income and expenses that we exclude from Adjusted EBITDA and Adjusted EBITDA Margin. Accordingly, we believe that these metrics provide useful information to investors and others in understanding and evaluating our results of operations, enhances the overall understanding of our past performance and future prospects, and allows for greater transparency with respect to key financial metrics used by our management in their financial and operational decision-making. We also believe that the presentation of these non-GAAP financial measures provides an additional tool for investors to use in comparing our core business and results of operations over multiple periods with other companies in our industry, many of which present similar non-GAAP financial measures to investors, and to analyze our cash performance.

The non-GAAP financial measures presented may not be comparable to similarly titled measures reported by other companies due to differences in the way that these measures are calculated. The non-GAAP financial measures presented should not be considered as the sole measure of our performance and should not be considered in isolation from, or as a substitute for, comparable financial measures calculated in accordance with GAAP. Further, these non-GAAP financial measures have certain limitations in that they do not include the impact of certain expenses that are reflected in our condensed consolidated statements of operations. Accordingly, these non-GAAP financial measures should be considered as supplemental in nature, and are not intended, and should not be construed, as a substitute for the related financial information calculated in accordance with GAAP. These limitations of Adjusted EBITDA and Adjusted EBITDA Margin include the following:

•The exclusion of certain recurring, non-cash charges, such as depreciation and amortization of property and equipment. While these are non-cash charges, we may need to replace the assets being depreciated in the future and Adjusted EBITDA does not reflect cash requirements for these replacements or new capital expenditure requirements;

•The exclusion of stock-based compensation expense, which has been a significant recurring expense and will continue to constitute a significant recurring expense for the foreseeable future, as equity awards are expected to continue to be an important component of our compensation strategy;

•The exclusion of other income, net, which includes interest income related to our cash, cash equivalents and short-term investments and realized and unrealized gains and losses on foreign currency exchange;

•The exclusion of strategic alternative expenses in connection with capital return strategies, buy- and sell-side mergers, acquisitions and partnerships which include integration costs, sale of a business or subsidiary, business optimization costs related to revisions of operational objectives and priorities which include restructuring charges, in all cases outside the ordinary course.

Because of these limitations, you should consider Adjusted EBITDA and Adjusted EBITDA Margin alongside other financial performance measures, including net loss and our other GAAP results. The information in the tables below sets forth the non-GAAP financial measures along with the most directly comparable GAAP financial measures.