We continue to wisely deploy capital by repurchasing 2.6 million shares of the company's common stock for $255 million.
We successfully reintroduced ourselves to the debt capital markets through the issuance of a $500 million 10-year bond with a coupon of 2.15%.
Net sales for the three months ended November 30, 2020, of $792 million decreased 5% compared with the prior-year period, due primarily to an estimated 4% decrease in the change in product prices and mix of products sold, as well as an estimated 1% decrease in sales volume.
Looking sequentially from the fourth quarter using the same calculations, price mix decreased 1%.
I'm encouraged with the net sales of $599 million through our independent sales network in which we saw a modest decrease of 3% due to the negative impact of the pandemic.
Sales in this channel of $76 million were down 9.5% in the quarter.
Our retail sales channel continues to be a bright spot with net sales up 3% to $55 million, driven largely by higher demand primarily for residential products.
Net sales in this channel of $24 million were down 28% as compared to the prior year.
I would like to highlight that our current quarter's gross profit margin of 42% was consistent with our fourth quarter gross profit margin even on lower sales.
Gross profit margin was $332 million, down approximately $23 million from the year-ago period.
Our SD&A expenses decreased approximately $19 million compared to the year-ago period.
Reported operating profit was $86 million, compared with $84 million in the year-ago period, while adjusted operating profit for the first quarter of 2021 was $104 million, compared with adjusted operating profit of $119 million in the year-ago period.
Reported operating profit margin was 10.8%, an increase of 80 basis points compared to the prior year.
Adjusted operating profit margin was 13.2%, a decrease of 110 basis points compared with the margin reported in the prior year.
The effective tax rate for the first quarter of fiscal 2021 was 24.7% compared with 22.9% in the prior-year quarter.
We currently estimate that our blended effective income tax rate before discrete items will approximate 23% for fiscal 2021.
Our diluted earnings per share for the first quarter of fiscal 2021 was $1.57, an increase of $0.13 per share or 9%.
Our adjusted diluted earnings per share this quarter of $2.03 was $0.10 lower than the prior year.
We generated $124 million of net cash provided by operating activities for the quarter ended November 30, 2020.
We invested $11 million or 1.4% of net sales in capital expenditures during the quarter.
We currently expect to invest approximately 1.5% of net sales in capital expenditures in fiscal 2021.
Additionally, during the first quarter of fiscal 2021, we repurchased 2.6 million shares for approximately $255 million or an average price of $100 per share.
We have approximately 5.1 million shares remaining under our current share repurchase board authorization.
At November 30, 2020, we had a cash and cash equivalents balance of $507 million.
As Karen mentioned, net sales of $791 million were 5% below the prior year.
I'm particularly pleased with the performance in our retail sales channel, which was up 3% over last year's first quarter and in our independent sales network, which was down 3% as compared to the prior year.
We also manage productivity and cost relative to price to maintain our gross margin at 42%.
This release is called ABT, Autonomous Bridging Technology and is designed to increase the overall range of the nLight AIR system in networked environments by 300%, taking connectivity more reliable.
In the first quarter, we repurchased 2.6 million shares of stock for $255 million.
Since we restarted our program during the fourth quarter, we have repurchased almost 8% of the company's stock.
We issued a $500 million 10-year bond at 2.15%.

Summary:
Net sales for the three months ended November 30, 2020, of $792 million decreased 5% compared with the prior-year period, due primarily to an estimated 4% decrease in the change in product prices and mix of products sold, as well as an estimated 1% decrease in sales volume.
Our diluted earnings per share for the first quarter of fiscal 2021 was $1.57, an increase of $0.13 per share or 9%.
Our adjusted diluted earnings per share this quarter of $2.03 was $0.10 lower than the prior year.