Thank you, Scott. Good morning, everyone, and thank you for joining us.
Before I review our record first quarter earnings, I will provide a few updates on our business as they relate to our capital and portfolio objectives, including our share repurchase efforts, and the sale of a small component of our print segment. I will also provide an update on our sustainability efforts. After my remarks, Steve will walk through our segment results, as well as our balance sheet and cash flow performance.
We will also provide an update to our outlook for the full year. The results in the first quarter continued to reflect progress toward our multi-year strategy to drive profitable growth, and become a leading full service provider of packaging products and supply chain solutions. Each of our segments is executing on their strategic objectives, and contributing to the profitability improvements reflected in the results. Strong earnings and disciplined working capital management allowed us to reduce net leverage, and expand capacity to deploy capital in support of our strategic priorities. Earlier this year, we announced a $50 million share repurchase plan to return value to shareholders. Through the end of the first quarter, we repurchased approximately $25 million of our shares, including approximately 550,000 shares from UWWH, the holding company owned by Bain Capital and Georgia Pacific. To provide some additional context, Bain Capital and Georgia Pacific were previously the owners of Unisource Worldwide. When Unisource Worldwide and xpedx merged to create Veritiv Corporation in July of 2014, UWWH held 49% of the shares of the new public company. Over time, UWWH liquidated portions of its stake in the company, and sold all of its remaining shares in the first quarter of this year.
As a result of this exit, partially facilitated by our share repurchase program, the downward pressure of a UWWH ownership position on our stock in the last few years has been lifted. We believe our share repurchase plan reflects a potentially high yielding deployment of capital, and we'll continue to execute against our plan.
As part of our efforts to focus on our core businesses, we recently completed the sale of our specialized paper converting business Roll Source, which was an operating unit within our print segment. The transaction was completed at the end of March. Pixelle Specialty Solutions, a current supplier to Veritiv, acquired this business as part of larger strategic moves in the print industry. The sale of the Roll Source specialty business will allow Veritiv to become even more focused on our core product and service offerings, and will not have a material impact on Veritiv's future earnings.
Moving now to our first quarter financial results.
We are pleased to report that the record financial performance from the fourth quarter of 2020 continued into the first quarter of this year. Robust packaging sales growth, stronger than expected print and publishing results, and operational efficiencies across the business led to adjusted EBITDA improvements across all segments compared to the prior year.
As a result, both pre-tax income and adjusted EBITDA reached record highs for the first quarter of $30 million and $60 million, respectively. This reflects a $30 million improvement in pre-tax income, and a $23 million increase in adjusted EBITDA, or plus 64% compared to prior year. Adjusted EBITDA margin remained at a record high of 3.8% in the first quarter, which was an improvement of 170 basis points compared to prior year.
Our packaging segment also achieved record adjusted EBITDA in the first quarter of $78 million, reflecting a 31% increase over prior year.
Continued improvement in demand and additional lift in price drove sales growth of 8% in the first quarter of 2021 compared to prior year, when adjusting for one less shipping day. Similar to last quarter, our customized solutions and capabilities in the food processing, specialty retail, consumer electronics, and healthcare sectors continue to drive strong sales performance and favorable customer mix. The ongoing shift by consumers to e-commerce remains a source of volume across several other end-use sectors.
Our automotive and aerospace manufacturing customers continue to recover, but at a slower pace than the general manufacturing sector, and have yet to return to pre-COVID levels.
We continue to closely monitor inflationary changes across our product portfolio and operations. Thus far, we have successfully mirrored recent supplier product cost increases to our customers in a timely manner, which has led to stable margins across all business segments through the first quarter. More specifically, corrugated sales were strong in the first quarter, due to both demand and multi-quarter industry-wide price increases. Weather-related impacts in February led to manufacturing production constraints, particularly with our suppliers of resin based products.
Fortunately, our national supply chain network ensured that the weather related impact to our customers was minimal. Because we are a national distribution company with no customer accounting for even 5% of our revenues, weather did not have a material impact to our financial results in the first quarter. I would now like to shift to a brief update on our efforts around sustainability. We view sustainability as more than a value add or a premium solution. It is a core responsibility, one that contributes to the wellbeing of our business, our people, and our planet.
Our team has been committed to helping our company and customers reduce environmental impacts for over a decade. We recently published an updated corporate social responsibility report, which can be found in the corporate responsibility and investor relations sections of our website.
We are proud of our progress, and eager to do even more.
Now Steve will provide additional details on our financial performance for the first quarter. Steve?