The company closed the second quarter with record sales of $2.654 billion and GAAP and adjusted diluted earnings per share of $0.59 and $0.61, respectively.
Sales were up 34% in U.S. dollars, 30% in local currencies and 22% organically compared to the second quarter of 2020.
Sequentially, sales were up 12% in U.S. dollars and in local currencies and 7% organically.
Orders for the quarter were a record $3.120 billion, which was up 58% compared to the second quarter of 2020 and up 14% sequentially, resulting in a very strong book-to-bill ratio of 1.18:1.
The interconnect segment, which comprised 96% of our sales, was up 34% in U.S. dollars and 30% in local currencies compared to the second quarter of last year.
Our cable segment, which comprised 4% of our sales, was up 27% in U.S. dollars and 24% in local currencies compared to the second quarter of last year.
GAAP and adjusted operating income were $476 million and $532 million, respectively, in the second quarter of 2021.
GAAP operating income includes $55 million of transactions, severance, restructuring and certain other noncash costs related to the MTS acquisition.
And the company also incurred $34 million related to the extinguishment of outstanding MTS senior notes that in accordance with GAAP was recorded as an increase to goodwill in the second quarter and therefore had no impact on the second quarter earnings.
Excluding these acquisition-related costs, adjusted operating margin was 20%, which increased by a strong 200 basis points compared to the second quarter of last year and increased by 40 basis points sequentially.
From a segment standpoint, in the interconnect segment, margins were 22% in the second quarter of 2021, which increased from 20% in the second quarter of 2020 and increased 50 basis points sequentially.
In the cable segment, margins were 6.1%, which decreased from 9.4% in the second quarter of 2020 and 8.8% in the first quarter.
The company's GAAP effective tax rate for the second quarter was 17.5%, which compared to 20.7% in the second quarter of 2020.
On an adjusted basis, this effective tax rate was 24.5% in the second quarter of both 2021 and 2020.
GAAP diluted earnings per share was $0.59, an increase of 40% compared to $0.42 in the prior year period.
And adjusted diluted earnings per share was a record $0.61, an increase of 53% compared to $0.40 in the second quarter of 2020.
Operating cash flow was $411 million in the second quarter or 109% of adjusted net income.
And net of capital spending, our free cash flow was $307 million or 81% of adjusted net income.
From a working capital standpoint, inventory days, days sales outstanding and payable days were 85, 71 and 60 days, respectively, all excluding the impact of acquisitions in the quarter and within our normal range.
During the quarter, the company repurchased 2.5 million shares of common stock for approximately $167 million at an average price of approximately $67.
At the end of the quarter, total debt was $5.2 billion and net debt was $4 billion.
Total liquidity at the end of the quarter was $2.3 billion, which included cash and short-term investments on hand of $1.2 billion plus availability under our existing credit facilities.
Second quarter 2021 GAAP EBITDA was $597 million, and our net leverage ratio was 1.6 times.
On a pro forma basis, after giving effect to the sale of MTS test and simulation business, net leverage at June 30, 2021 would have been 1.3 times.
Craig already mentioned, our sales grew a very strong 34% in U.S. dollars and 30% in local currencies, reaching a new record of $2.654 billion.
On an organic basis, our sales increased by 22%, with growth driven in particular by the automotive, military, industrial and broadband markets as well as contributions from the company's acquisition program.
We're very pleased to have booked record orders in the quarter of $3.120 billion and that represented a very strong book-to-bill of 1.18:1.
Despite facing operational challenges in certain geographies related to the ongoing pandemic as well as continued increases in costs related to commodities and supply chain pressures, we were very pleased to deliver very strong adjusted operating margins of 20% in the quarter.
This was a 200 basis point increase from last year's levels and a 40 basis point improvement sequentially.
Adjusted diluted earnings per share grew a very significant 53% from prior year to another new record of $0.61.
And finally, the company generated operating and free cash flow of $411 million and $307 million, respectively, in the second quarter.
Unlimited is based in Oconto, Wisconsin, but also with operations in Mexico and has annual sales of approximately $50 million.
The military market represented 11% of our sales in the quarter.
And as expected, sales grew a strong 45% from the COVID impacted prior year second quarter and were up 30% organically.
On a sequential basis, sales increased by 12%, also very strong.
The commercial air market represented 2% of our sales in the quarter.
Sales grew by 7% versus prior year, really with the benefit of the contributions of our recent acquisitions.
On an organic basis, sales were down by about 14% as the commercial aircraft market continued to experience declines in demand for new aircraft production.
Sequentially, however, our sales did increase by better than expected 19%.
The industrial market represented 27% of our sales in the quarter, and our performance in the second quarter in industrial was really much stronger than expected with sales increasing by 54% in U.S. dollars and 28% organically.
On a sequential basis, sales increased by a very strong 26% from the first quarter really with the benefit of acquisitions as well as strong organic performance.
The automotive market represented 20% of our sales in the quarter.
And I can just say that sales were higher than our expectations, growing a very strong 134% in U.S. dollars and 117% organically as our team was able to execute strongly in the face of a robust and broad recovery in the automotive market.
That market represented 10% of our sales in the quarter.
Our sales to customers in the mobile devices market declined from prior year by 4% in U.S. dollars and 6% organically as declines in handsets and laptops more-than-offset growth in wearables.
Sequentially, our sales fell by 6% from the first quarter, which was modestly better than our expectations.
Looking to the third quarter, we now expect an approximately 25% increase in sales from these second quarter levels as we benefit from the seasonally typical higher demand in the mobile device market as customers launch a range of new products.
The mobile networks market represented 5% of our sales in the quarter.
Sales were flat to prior year and down 4% organically as sales to both OEMs and wireless service providers moderated.
On a sequential basis, however, our sales increased by 5% compared to the first quarter, which was in line with our expectations coming into the second quarter.
The information technology and data communications market increased by 21% in the second quarter.
Sales in the second quarter rose by 5% in U.S. dollars and 3% organically from the very significant levels in last year's second quarter.
Our strength this quarter was driven, in particular, by robust sales to web service providers, which was partially offset by some weakness in sales to networking equipment OEMs. Sequentially, our sales grew a very strong 20% from the first quarter, which significantly outperformed our original expectations.
This market represented 4% of our sales in the quarter, and sales increased by 12% from prior year and were flat organically as we benefited from our recent acquisition of Cablecon.
On a sequential basis, sales increased by 7% from the first quarter, which was a bit lower than we had anticipated coming into the quarter.
And I would just note that given the current dynamic market environment, and of course, assuming no new material disruptions from the COVID-19 pandemic as well as constant exchange rates, in the third quarter, we expect sales in the range of $2.640 billion to $2.700 billion, and adjusted diluted earnings per share in the range of $0.60 to $0.62.
This would represent sales growth of 14% to 16% and adjusted diluted earnings per share growth of 9% to 13% compared to the third quarter of last year.

Summary:
The company closed the second quarter with record sales of $2.654 billion and GAAP and adjusted diluted earnings per share of $0.59 and $0.61, respectively.
GAAP diluted earnings per share was $0.59, an increase of 40% compared to $0.42 in the prior year period.
And adjusted diluted earnings per share was a record $0.61, an increase of 53% compared to $0.40 in the second quarter of 2020.
Adjusted diluted earnings per share grew a very significant 53% from prior year to another new record of $0.61.
And I would just note that given the current dynamic market environment, and of course, assuming no new material disruptions from the COVID-19 pandemic as well as constant exchange rates, in the third quarter, we expect sales in the range of $2.640 billion to $2.700 billion, and adjusted diluted earnings per share in the range of $0.60 to $0.62.
This would represent sales growth of 14% to 16% and adjusted diluted earnings per share growth of 9% to 13% compared to the third quarter of last year.