Our revenue in the first quarter was a record of nearly $1.14 billion, an increase of 24% and surpassed last quarter's record by more than $75 million, driven by record revenue in both our Global Wealth Management and Institutional Groups.
The growth in revenue and our focus on expense management resulted in non-GAAP earnings per share of $1.50, which was up 88% year-on-year and represented the second highest quarterly earnings per share in our history.
Pretax margins of more than 21%, annualized return on tangible common equity of over 28% and tangible book value, which increased 32%.
As I stated, our first quarter net revenue increased 24% to a record surpassing $1.1 billion.
Compensation as a percentage of net revenue came in at 60.9%, which was just above the high end of our annual range, yet is consistent with our policy of accruing for compensation conservatively early in the year.
Our operating expense ratio was about 18%.
But excluding credit provision and investment banking gross-ups, our operating expense ratio totaled approximately 16%.
This, coupled with strong credit performance in our loan portfolio, resulted in a relief of $5 million of our credit provisions during the quarter.
So neutralizing the impact of credit provisions, Stifel's pre-tax pre-provision income totaled $238 million, which increased 61% from the first quarter of 2020.
First quarter revenue totaled a record $631 million, up 8% year-on-year.
While this increase is impressive, I believe it understates the strength of our business as it includes a nearly $24 million decline in net interest income at our bank subsidiary.
Excluding the impact of lower bank NII, our private client business improved 13%, driven by the strength in asset management as well as growth in brokerage revenue, as we benefited from enhanced client activity levels and continued success in recruiting.
Total assets under administration of nearly $380 billion increased $21 billion from the prior quarter.
Additionally, fee-based assets of $138 billion rose 7% sequentially, which should drive further growth in the asset management and service fees line item in the second quarter of this year.
We had a solid quarter in terms of advisor additions as we added 15 advisors with total trailing 12-month production of $13 million.
Since the beginning of 2019, we've added 300 financial advisors with cumulative production of approximately $233 million.
In the first quarter, we announced that we were rebranding Century Securities, which we've operated since 1990 as Stifel Independent Advisors.
Net revenue totaled $506 million, which was up 52% from the prior year and surpassed last quarter's record by approximately $15 million.
We generated a 23% pre-tax operating margin, which was up more than 1,000 basis points from the same period a year ago.
Looking at the revenue components of our institutional business, I would note that our equities business totaled $226 million, up 74%; while fixed income totaled $146 million, which increased 10% from the comparable first quarter of 2020.
With respect to our trading businesses, we generated record equity brokerage revenue in the first quarter, surpassing our prior record set a year ago by 13% as strong activity levels continued and trading gains increased.
Fixed income brokerage revenue in the quarter was up 12% sequentially and represented our third highest quarterly revenue, trailing only the first and second quarter of last year.
On Slide seven, investment banking revenue of $339 million was our second consecutive quarterly record, surpassing last quarter's record by a few million dollars, driven primarily by record capital raising revenue.
Equity underwriting revenue was standout in the quarter, coming in at $160 million and surpassing the record we set last quarter by nearly $50 million.
This is a good example of how, by investing in our business over the last several years, we've become a more significant player as we were a book runner on more than 50% of the IPOs we participated in the quarter.
However, SPACs accounted for a little more than 15% of our equity underwriting revenue in the quarter.
Our fixed income underwriting revenue of $49 million was a record for the first quarter and was up 43% year-on-year.
Our municipal finance business rebounded from challenging market conditions in the first quarter of 2020 as we lead manage 236 municipal issues, which represented an increase of 42%.
Regarding our advisory business, revenue of $130 million represented our third highest quarterly revenue and a record by almost 25% for any first quarter.
In the quarter, we generated the second highest GAAP earnings per share in our history at $1.40, which was only surpassed by the results generated last quarter.
We again generated strong returns on equity with an ROE of 18% and ROTCE of nearly 27%.
This was accomplished while increasing assets by $1.5 billion, resuming our open market share buyback program and given the seasonal impact of stock compensation on equity in the first quarter.
For the quarter, net interest income totaled $113 million, which was up $8 million sequentially.
Our firmwide net interest margin increased to 200 basis points, and our bank's net interest margin improved to 240 basis points.
Both NII and NIM benefited from the remix of bank assets out of our securities portfolio and into our loan portfolio as well as growth in our average interest-earning asset levels by 6% during the quarter.
As such, in terms of the second quarter, we expect net interest income to be in a range of $110 million to $120 million and with a similar NIM to the first quarter.
As an update to what we discussed last quarter, assuming a 100 basis point increase in rates across the curve and a 30% deposit beta, we would generate an additional $150 million to $175 million of pre-tax earnings.
But for this analysis, we used a 30% deposit beta.
We ended the period with total net loans of $12.2 billion, up approximately $1 billion from the prior quarter.
Our mortgage portfolio increased by $200 million sequentially, and as we continue to see demand for residential loans from our wealth management clients despite the increase in interest rates during the quarter.
Our securities-based loan portfolio increased by approximately $170 million.
Our commercial portfolio accounts for 39% of our total loan portfolio and is primarily comprised of C&I loans, which increased by 15% during the quarter.
Our portfolio is well diversified with our highest sector exposure in fund banking and PPP loans, each representing approximately 5% of the portfolio.
PPP loans accounted for more than $400 million of C&I growth, while fund banking accounted for $260 million.
This can be seen in the fair value of the portfolio, which was at an average price of 99.9% of amortized cost at quarter end.
We increased our CLO holdings by 7% from last quarter in anticipation of some payoffs expected to occur in the second quarter.
We had a $5 million reversal of our allowance through a negative provision expense as additional reserves tied to loan growth were more than offset by the improved economic scenario in our CECL calculation.
As a result of the reserve release and the composition of our loan growth during the quarter, our ratio of allowance to total loans declined to 118 basis points, excluding PPP loans.
At quarter end, the consumer allowance to total loans was 31 basis points, while the commercial portfolio was at 174 basis points.
Further, we did take the opportunity to derisk from our commercial book by selling or reducing positions by $83 million on five C&I loans, which resulted in less than $1 million of charge-offs.
This equates to a roughly 1% discount to bar.
Our risk base and leverage capital ratios came in at 19.4% and 11.5%.
The decline in our capital ratios was driven by balance sheet growth and the $68 million impact in equity to net settle taxes on our issues in the first quarter.
We repurchased approximately 195,000 shares at an average price of $61.79 per share.
Our book value per share increased to $35.96, up modestly from the prior quarter as the impact of net income on equity was offset by the aforementioned vesting of restricted stock.
Our tangible book value per share increased to $23.93.
The total third-party cash REIT program increased by approximately 5% during the quarter, which was used to fund the aforementioned bank growth.
In the first quarter, our pre-tax margin improved 730 basis points year-on-year to more than 21%.
Our comp-to-revenue ratio of 60.9% was down 160 basis points from the prior year.
That ratio came in above our full year range of 58.5% to 60.5% and is consistent with our strategy to be conservative in our compensation accruals early in the year given the transactional nature of a large portion of our business.
Noncomp opex, excluding the credit loss provision and expenses related to investment banking transactions, totaled approximately $184 million and represented approximately 16% of net revenue.
The effective tax rate during the quarter came in at 24.1%, which was driven by the impact of the excess tax benefit related to stock compensation.
Absent any other discrete items, we would expect to see the effective rate to be in the 25% to 26% range in the second and third quarters as we have limited RSU vesting that occurs before the fourth quarter.
In terms of our share count, our average fully diluted share count was up 1% primarily as a result of the increase in our share price.
Absent any assumption for additional share repurchases and assuming a stable stock price, we'd expect the second quarter fully diluted average share count to total 118.7 million shares.
With respect to our full year revenue guidance of $3.8 billion to $4 billion, based on what I'm seeing in our outlook, we are tracking above the high end of our full year guidance.
Our asset management fees will benefit from the 7% increase in fee-based assets last quarter.
The $1.5 billion in balance sheet increase represents 75% of our full year guidance.

Summary:
The growth in revenue and our focus on expense management resulted in non-GAAP earnings per share of $1.50, which was up 88% year-on-year and represented the second highest quarterly earnings per share in our history.
As I stated, our first quarter net revenue increased 24% to a record surpassing $1.1 billion.
In the quarter, we generated the second highest GAAP earnings per share in our history at $1.40, which was only surpassed by the results generated last quarter.