Thank you, Kim. Good morning, everyone. And thank you all for joining us today to discuss our second quarter 2021 financial results. I will begin with a high level overview of our second quarter performance and capital allocation priorities. Karla will then speak to our operating results and demand trends by end market. And Arthur will conclude with a review of our second quarter 2021 financials.
Our resilient business model, coupled with favorable market conditions drove a second consecutive quarter of record financial performance. I am inspired by the ongoing operational excellence and performance demonstrated by all of my colleagues within the Reliance family of companies. Despite lingering disruptions associated with the global pandemic, including limited metal availability, and various other supply chain constraints, our managers in the field exhibited tremendous execution and most importantly, maintain the relentless focus on safety.
During the second quarter, we continued to experience considerable strength in metals pricing, led by multiple mill price increases for carbon and stainless steel products in particular. The favorable pricing environment along with continued strong underlying demand in the majority of the end markets we serve drove record quarterly net sales of $3.42 billion.
Our business model, which is strategically highly diversified in terms of our products, end markets and geographies, and focused on small order sizes with quick turnaround, is particularly effective during periods of tight supply and volatile pricing.
In addition, despite metal supply constraints, our strong, long-standing relationships with the domestic mills and our unique ability to cross-sell inventory among our Family of Companies allowed us to source the metal we needed to satisfy our valued customers. Through continued pricing discipline by our managers in the field, we generated a strong gross profit margin of 31.7% which, when combined with our record sales, resulted in record quarterly gross profit of $1.08 billion in the second quarter of 2021. Both our record quarterly gross profit and our continued focus on expense control contributed to our second consecutive quarter of record quarterly pretax income of $444.1 million.
Our quarterly earnings per diluted share of $5.08 were both another record and substantially in excess of our guidance as well as up 23.3% from our prior quarter.
Our resilient and continuously improving business model has enabled us to maintain industry leading gross profit margins throughout various metals pricing and demand cycles. We most recently increased our long-term sustainable gross profit margin range to 28% to 30% during the first quarter of 2020, and we have remained above this range throughout the uncertain COVID-19 pandemic environment. We believe our sustainable outperformance resulted from our managers disciplined approach to pricing and increased value added processing that led to a greater focus on high quality high margin business. Today, we are very pleased to announce that we are once again increasing our estimated sustainable gross profit margin range to 29% to 31%.
We are confident in our ability to maintain this higher range on an annual basis as a result of our sustainable impacts the investments we have made in our business are having on our gross profit margins.
Let me touch on this a little bit more in detail.
Over the past five years, we have invested nearly a $1 billion into our company through capital expenditures, approximately half of which was directly - that was directed towards state of the art value added processing equipment across the family of companies. These investments not only introduced new processing capabilities, and help us increase the percentage of orders with processing from our historic levels of about 40% to our current level of about 50%, but also enhanced and upgraded our existing value added processing equipment to improve the quality of our service offerings to our customers.
Our investments within our family of companies enables our managers in the fields to provide additional value to our customers and an appropriate price, which further supports our increased sustainable gross profit margin rage.
Looking ahead, we will continue to prioritize investing in our company's growth as a key element of our capital allocation strategy. We maintain a flexible capital allocation strategy that is focused on both reinvesting in our company's growth and stockholder returns.
Beyond the significant investments, we are continuing to make in value added processing equipment, our 2021 capital expenditures will also be focused on both new facilities and projects to expand, upgrade and maintain many of our existing operations.
As such, we are increasing our 2021 capital expenditure budget from $245 million to a new record of $310 million due to various key projects, including a significant expansion of our operation in South Korea, that services the semiconductor and biochem and pharma markets, new expansion - new expanded total processing capacity and increased investments in renewable energy at many of our existing facilities.
During the second quarter of 2021, we invested $80.1 million in capital expenditures.
Turning to our other avenue of growth acquisitions, we have a healthy pipeline of prospective opportunities, including both traditional metal service center businesses and adjacent businesses.
As always, we would adhere to our strict transaction criteria when evaluating prospective targets to ensure a strong fit within our family of companies. In regard to stockholder returns, we returned $67.8 million to our stockholders during the second quarter of 2021 through the payment of $43.8 million in dividends, and the repurchase of $24 million of Reliance, common stock.
As announced earlier today in our earnings release, our Board of Directors approved an amendment of our share repurchase plan that was set to expire at the end of this year, increasing our repurchase authorization to $1 billion. Since 2018, we have repurchased approximately $900 million of our common stock at a weighted average cost of $85.52 per share.
We expect to remain a prudent allocator of capital by maintaining our flexible approach focused on both growths, which remains a top priority as well as stockholder return activities.
Finally, I would like to briefly comment on our recently announced executive officer succession matters. Effective January 2020, Bill Sales will retire from Reliance following 24 years of service with our company, as of July 1st, Bill transition from his role as Executive Vice President of Operations to Special Advisor, where he will provide support on special projects to facilitate the transition of those responsibilities. Bill's deep industry experience and relationships have contributed significantly to Reliance and our success over the years. I'd like to sincerely thank you, Bill, for all your hard work and dedication to the company. And on behalf of all of us at Reliance, wish you the very best in your retirement. Relatedly as a part of our deliberate succession planning process I'd also like to congratulate both Sean Mollins who has been promoted to Senior Vice President, Operations, and Brian Yamaguchi, who has been promoted to Vice President, Supplier Development. Both Sean and Brian have a long standing history with Reliance, as well as a significant industry experience and a passion for our business. I applaud both of you for your well-deserved new roles. In summary, I am beyond inspired by the outstanding operational execution demonstrated by the entire Reliance team, and their unwavering focus on the core elements of our resilient business model, which drove our second consecutive quarter of record financial performance in an environment characterized by extremely high metals pricing, strong demand from our customers and limited metal availability. We believe Reliance remains well positioned to continue supporting the growth and needs of our customers and our suppliers while generating strong earnings and returning value to our stockholders. We remain confident that America is going to need Reliance to rebuild, and we will continue to support our colleagues, customers, suppliers and community in collective efforts to do so. Thank you very much for your time and attention today. I will now turn the call over to Karla to review our operating results and demand trends. Karla?