Overall, Domino's team members and franchisees around the world generated impressive operating results, leading to a diluted earnings per share of $3 for the first quarter.
Global retail sales grew 16.7% in Q1 as compared to Q1 2020.
When excluding the positive impact of foreign currency, global retail sales grew 14%.
Breaking down that global retail sales growth, our US retail sales grew 15.3% and our international retail sales grew 18%.
When excluding the positive impact of foreign currency, international retail sales grew 12.8%.
During Q1, we continued to lead the broader restaurant industry with 40 straight quarters of positive US comparable sales and 109 consecutive quarters of positive international comps.
Same-store sales in the US grew 13.4% in the quarter, lapping a prior year increase of 1.6%.
Same-store sales for our international business grew 11.8%, rolling over a prior year increase of 1.5%.
Our franchise business was up 13.9% in the quarter, while our Company owned stores were up 6.3%.
The 11.8% international comp was driven by ticket growth.
We and our franchisees added 36 net stores in the [Technical Issues] US during the first quarter, consisting of 37 store openings and the closure of one of our corporate stores.
Our international business added 139 net stores, comprised of 160 store openings and 21 closures.
Total revenues for the first quarter were approximately $984 million and were up approximately $111 million or 12.7% over the prior year quarter.
Changes in foreign currency exchange rates positively impacted our international royalty revenues by $2.1 million in Q1 2021 as compared to prior year.
Our consolidated operating margin as a percent of revenue increased to 39.6% in Q1 2021 from 39% in the prior year, due primarily to higher revenues from our US franchise business.
Company-owned store margin as a percent of revenues increased to 23.9% from 22.4%, primarily as a result of strong sales leverage.
This was also up sequentially from 21.9% in Q4 2020, driven by lower labor cost as a percent of revenue in Q1 2021.
Supply chain operating margin as a percent of revenues decreased to 10.5% from 11.5% in the prior year quarter.
G&A expenses increased approximately $2.8 million in Q1 as compared to Q1 2020 resulting from a combination of higher advertising expenses and labor costs, partially offset by travel.
Net interest expense increased approximately $0.9 million in the quarter, primarily the result of lower interest income.
As previously disclosed, in Q1 2021, we invested an additional $40 million in Dash brands, our master franchisee in China, following their achievement of previously established performance conditions.
Accordingly, we remeasured the original $40 million investment we made in Q2 of last year due to the observable change in price from the valuation of the additional investment.
This $2.5 million gain was recorded in other income in the first quarter of 2021.
Our effective tax rate was 21.3% for the quarter as compared to a negative 3.7% in Q1 2020.
The effective tax rate in Q1 2021 includes a 0.6 percentage point positive impact from tax benefits on equity-based compensation as compared to a 26 percentage point positive impact in Q1 2020.
Combining all of these elements, our first quarter net income was down $3.8 million or 3.2% versus Q1 2020.
On a pre-tax basis, income before provision for income taxes was up $32.3 million or 27.6%.
Our diluted earnings per share in Q1 was $3 versus $3.07 in the prior year, a decrease of 2.3%.
Breaking down that $0.07 decrease, most notably, our improved operating results benefited us by $0.61.
The gain on the Dash brands investment benefited us by $0.05.
Net interest expense negatively impacted us by $0.02.
A lower diluted share count driven by share repurchases over the trailing 12 months benefited us by $0.03.
And finally, our higher effective tax rate resulting from lower tax benefits on equity-based compensation, as I mentioned previously, negatively impacted us by $0.74.
During Q1, we generated net cash provided by operating activities of approximately $153 million.
After deducting for capex, we generated free cash flow of approximately $136 million.
Regarding our capital expenditures, we spent approximately $17 million on CapEx in Q1, primarily on our technology initiatives.
As previously disclosed, during Q1, we also repurchased and retired approximately 66,000 shares for $25 million.
As a reminder, in February, our Board approved a new $1 billion authorization for future share repurchases.
We also paid a $0.94 quarterly dividend on March 30.
Subsequent to the end of the quarter, our Board of Directors declared a quarterly dividend of $0.94 per share to be paid on June 30.
We're very pleased with our gross issuance of $1.85 billion, which includes $850 million of seven-and-a-half-year to 2.662% fixed-rate notes and $1 billion of 10-year 3.151% fixed-rate notes.
This recapitalization will reduce our weighted average borrowing rate from 3.9% as of the end of the first quarter to approximately 3.7%.
And it will return our leverage to approximately 6 times EBITDA, consistent with our leverage model following previous recapitalizations.
Our US business performed extremely well during the quarter, highlighted by 15.3% retail sales growth and a 13.4% comp.
At 15% for the first quarter, we saw a slight sequential improvement of the two-year stack when compared to the fourth quarter of 2020.
Now, beyond the comps, when you look at the absolute dollars, our first quarter same-store average weekly unit sales in the US exceeded $26,000.
Our addition of 36 net stores was a nice improvement over Q1 of 2020 and we anticipate a strong pipeline of future openings.
A single store closure in the quarter, on a base of over 6,000 units, demonstrates the elite economic proposition that we offer to our franchisees.
And on that note, I'm thrilled to report yet another record-setting year of franchisee profitability, with our final 2020 estimated average EBITDA number for US franchise stores coming in at just over $177,000; the highest in our history.
Our 12.8% retail sales growth was supported by a very strong 11.8% comp, continuing the momentum we saw toward the end of last year.
Q1 represented a 13.3% two-year stack, which was a 430 basis point improvement versus the fourth quarter of 2020.
Our 139 net stores in Q1 was a 100-store improvement versus the first quarter of 2020.
We continue to have temporary store closures around the world, but those have come down dramatically over the last few quarters and were below 100 at the end of the first quarter.
And we remain confident in our two-year to three-year outlook of 6% to 8% annual net store growth and 6% to 10% annual global retail sales growth.

Summary:
Global retail sales grew 16.7% in Q1 as compared to Q1 2020.
Same-store sales in the US grew 13.4% in the quarter, lapping a prior year increase of 1.6%.
Same-store sales for our international business grew 11.8%, rolling over a prior year increase of 1.5%.
The 11.8% international comp was driven by ticket growth.
Total revenues for the first quarter were approximately $984 million and were up approximately $111 million or 12.7% over the prior year quarter.
Our US business performed extremely well during the quarter, highlighted by 15.3% retail sales growth and a 13.4% comp.
Our 12.8% retail sales growth was supported by a very strong 11.8% comp, continuing the momentum we saw toward the end of last year.