Thank you, Chuck. I would now like to discuss our quarterly financial results, particularly key P&L cash flow and balance sheet highlights.
As Chuck mentioned, we continue to have record financial performance. In the quarter, we reported record revenues of $457.9 million versus $411.2 million last year, a growth of 11.4% in the quarter.
First quarter 2021 revenues were close to the top end of our revenue outlook range of $454 million to $459 million. On a year-over-year comparable basis, first quarter 2021 revenues included a $13.9 million revenue contribution from the Penny Hoarder acquisition and an $11.5 million foreign exchange benefit.
Excluding the acquisition in foreign exchange benefit, first quarter revenues were up approximately $21.3 million or 5.2% constant currency organic revenue growth, thanks to our agility and our diverse business mix. By vertical market and an organic constant basis, health care was up around 51%; others, which includes retail up 22% technology, technology up around 10%, financial services up approximately 6%, all of which more than offset 33% decline in travel and transportation and 7% decline in communications vertical. The tougher comps in the communications vertical expects to lot in the third quarter of 2021.
First quarter 2021 operating income increased 29.3% to 31.5 million, with operating margins increasing to 6.9% from 5.9% for the comparable period last year. On a non-GAAP basis, which excludes the impact of impairment of right of use assets and other fixed assets related to COVID-19 driven facility exits, acquisition related intangible amortization, merger and integration costs and other costs related facility access.
First quarter 2021 operating margin was 8% versus 7.2% in the same period last year. The increase in the comparable operating margin was due to strong overall demand, higher capacity utilization and cost benefits of COVID-19 related facilities rationalization, partially moderated by approximately 60 basis points of impact from a true-up in long-term incentive comp as well as client ramp costs and IT and IT-related investments to reinforce the company's infrastructure and agility in the marketplace. The year ago operating margin was also moderated by approximately net 70 basis points impact from COVID-19 related lockdowns, including government mandated wage payments to unavailable absent employees without the corresponding revenues, cost of temporary workspace accommodations, employee transportation and facility sanitization costs.
First quarter 2021 diluted earnings per share increased 85.3% to $0.63 versus $0.34 in the same period last year. On a non-GAAP basis, the first quarter 2021 diluted earnings per share was $0.73 cents versus $0.44 cents, up 65.9% on a comparable basis. The increase was driven by a combination of factors, including strong operating performance, lower other expenses, contributions from the Penny Hoarder acquisition, lower effective tax rate and lower share count.
First quarter 2021 non-GAAP diluted earnings per share exceeded the midpoint of the $0.67 to $0.70 guidance range by $0.04 per share, which was driven by a lower-than-projected tax rate.
Turning to our client mix, on a consolidated basis, our top 10 clients represented approximately 40% of total revenues during the first quarter of 2021, down from 45% in the year ago period. The decline of function of both broad-based growth outside of our top 10 clients and the contribution of the Penny Hoarder acquisition.
In fact, we had no 10% client in both comparable quarters.
Now let me turn to select cash flow and balance sheet items.
During the quarter, cash flow from operations jumped 41.1% to $40.2 million from $28.5 million due to a combination of strong earnings and working capital swing factors. Capital expenditures decreased to 2.1% of revenues from 2.9% of revenues in the year ago period. The decrease was largely timing driven. The company continues to invest in PC refresh, IT security and targeted capacity expansion. Trade DSO on a consolidated basis for the first quarter were 80 days, unchanged comparably and down 1 day sequentially. The DSO was 80 days for Americas, 82 days for EMEA.
Our balance sheet at 31st of March remains strong with cash and cash equivalent of $112.8 million, of which approximately $87.2 million or $98.3 million was held in international operations. At the quarter end, we had $48 million in borrowings outstanding, down from $63 million at the year end, under our 500 million credit facility.
We continue to hedge some of the foreign exchange exposure for the second quarter and full year was hedged approximately 35% and 6% at a weighted average rate of PHP48.78 and PHP48.98 to the U.S. dollar.
In addition, our Costa Rica colón exposure for the second quarter and full year is hedged at approximately 37% and 28%, at weighted average rates of CRC 584.72 and CRC 586.43 to the U.S. dollar.
Now let's turn to some seat count and capacity utilization metrics. On a consolidated basis, we ended first quarter with approximately 45,100 seats, down approximately 3,500 seats comparably. The reduction in capacity reflects decisions made by certain clients to permanently alter the delivery mix away from brick-and-mortar to a home agent solution due to COVID-19, coupled with consolidation of underutilized facilities.
The first quarter seat count can be further broken down to 7,600 in Americas and 7,500 in EMEA region, from 40,600 and 8,000, respectively in year ago quarter. Capacity utilization rates at the end of the first quarter of 2021 were 74% for the Americas and 71% for the EMEA region versus 74% for Americas and 69% for EMEA in year ago quarter. The capacity utilization rate on a combined and comparable basis increased to 74% from 73% year ago period. Including permanent home agent and the comparable utilization calculation would have increased the comparable capacity utilization even further.
Now let's turn to business items.
We are increasing a full year 2020 revenue and diluted earnings per share outlook relative to the initial guidance provided back in February 2021. The increase in the revenue outlook is driven by a broad base of existing clients across the company's vertical markets while the increase in diluted earnings per share is primarily due to a lower-than-projected tax rate.
Second, we continue to work with clients in determining future view of the delivery strategy between home agent and brick-and-mortar facilities driven by COVID-19.
As such, we continue to adjust their capacity footprint similar to actions taken in facility leases in 2020 as we get greater clarity around those decisions.
Third, our revenues and earnings per share assumptions for the second quarter and full year are based on foreign exchange rates as of April 2021. Therefore, the continued volatility in foreign exchange rates between the U.S. dollar and the functional currencies of the markets we serve could further impact positive or negative on revenues on both GAAP and non-GAAP earnings per share relative to the business outlook for the second quarter and full year. Fourth, we anticipate total other interest income expense net of approximately $1.4 million and $4.8 million for the second quarter and full year, respectively. In the second quarter, roughly $1 million of the $1.4 million reflects the previously discussed impact of the company's stake in XSELL technologies, which is poised to accelerate its growth investments in its business and is a candidate under the equity method. The remainder reflects the interest expense related to the acquisition of the Penny Hoarder. The amount and the other interest income expense net, however, exclude the potential impact of any foreign exchange gains or losses.
Finally, we expect a full year 2021 effective tax rate to be lower than previously projected due to discrete benefits relating to the Philippines tax reform as well as stock compensation. Considering the above factors, we anticipate the following financial results for the 3 months ending June 30, 2021. Revenues in the range of $443 million to $448 million, effective tax rate of approximately 23% on both GAAP and non-GAAP basis, fully diluted shared count of approximately 39.9 million, diluted earnings per share of approximately $0.46 to $0.50, non-GAAP diluted earnings per share in the range of $0.56 to $0.60 and capital expenditures in the range of $15 million to $20 million.
For the 12 months ending December 31, 2021, we anticipate the following financial results. Revenues in the range of $1.843 billion to $1.858 billion, effective tax rate of approximately 21% and 22% on a non-GAAP basis, fully diluted shared count of approximately 40.1 million, diluted earnings per share of approximately $2.67 to $2.77, non-GAAP diluted earnings per share in the range of $3.02 to $3.12, capital expenditures in the range of $47 million to $53 million. With that, I'd like to open the call up for questions. Operator?