We are proud to announce that Prosperity Bank has been rated in the Top 10 of Forbes Best Banks in America for the seventh consecutive year, and we are the highest rated Texas bank -- the highest rated Texas-based banks.
One, there was a one-time charge of $46.4 million related to the merger.
For the first quarter of 2020, we expect approximately $13 million to $14 million pre-tax in loan discount accretion.
Net income was $86.1 million for the three months ending December 31, 2019, compared with $83.3 million for the same period in 2018.
Our earnings per diluted common share were $1.01 for three months ending December 31, 2019, compared with the $1.19 for the same period in 2018, and were impacted by merger-related expenses of $46.4 million.
It should also be noted that earnings per share is calculated based on average shares outstanding, which were 85,573,000 for the fourth quarter.
We issued approximately 26,228,000 shares in the Merger.
As of December 31, 2019, we had 94,746,000 shares outstanding.
Loans at December 31, 2019, were $18.8 billion, an increase of $8.4 billion or 81.7% compared with $10.3 billion at December 31, 2018.
Linked-quarter loans increased $8.1 billion or 76.6% from the $10.6 billion at September 30, 2019.
Excluding loans acquired in the Merger and new production by the acquired lending operations since November 1, 2019, loans at December 31, 2019, grew $218 million or 2.1% compared with December 31, 2018, and decreased $84 million or 80 basis points on a linked-quarter basis.
The Average loans, excluding the impact of the Merger, increased $407 million or 4% during 2019.
Deposits at December 31, 2019 were $24.2 billion, an increase of $6.9 billion or 40.2% compared with $17.257 billion at December 31, 2018.
Our linked-quarter deposits increased $7 billion -- $7.2 billion or 42% from $16.9 billion at September 30, 2019.
Excluding deposits assumed in the Merger and new deposits generated at the acquired banking centers since November 1, 2019, deposits at December 31, 2019 increased $801 million or 4.6% compared with December 31, 2018, and increased $1.1 billion or 6.7% on a linked-quarter basis.
Asset quality or non-performing assets totaled $62.9 million or 25 basis points of quarterly average interest-earning assets at December 31, 2019 compared with $18.9 million or 10 basis points of quarterly average interest-earning assets at December 31, 2018, and $51 million or 26 basis points of quarterly average interest-earning assets at September 30, 2019.
We announced today that our Board of Directors has authorized a share repurchase program under which the Company can purchase up to 5% of its outstanding common stock, approximately 4.7 million shares over the next year.
So overall, despite oil and gas prices remaining in the $55 to $60 per barrel range, Texas and Oklahoma continued to experience employment and population growth, with many companies moving to these states because of the favorable tax environments and business-friendly political climates.
Net interest income before provision for credit losses for the three months ended December 31, 2019 was $232 million compared to $157.2 million for the same period in 2018, an increase of $74.8 million or 47.6%.
The net interest margin on a tax equivalent basis was 3.66% for the three months ended December 31, 2019 compared to 3.15% for the same period in 2018, and 3.16% for the quarter-ended September 30, 2019.
Excluding purchase accounting adjustments, the core net interest margin for the quarter-ended December 31, 2019 was 3.26% compared to 3.1% for the same period in 2018, and 3.14% for the quarter-ended September 30, 2019.
Noninterest income was $35.5 million for the three months ended December 31, 2019 compared to $29.1 million for the same period in 2018.
Noninterest expense for the three months ended December 31, 2019 was $156.5 million compared to $80.8 million for the same period in 2018.
The increase was primarily due to the merger-related expenses of $46.4 million and two months of LegacyTexas expenses.
Until the conversion, sorry, until the system integration and conversion, we expect noninterest expense to range around $120 million to $125 million per quarter, those are excluding any additional merger-related expenses.
The efficiency ratio was 58.07% for the three months ended December 31, 2019 compared to 43.2% for the same period in 2018 and 43.7% for the three months ended September 30, 2019.
Excluding merger-related expenses, the efficiency ratio was 40.85% for the three months ended December 31, 2019.
The bond portfolio metrics at 12/31/2019 showed a weighted average life of 3.42 years and projected annual cash flows of approximately $2 billion.
Nonperforming assets at quarter-end December 31, 2019 totaled $62.943 million or 33 basis points of loans and other real estate.
The December 31, 2019 nonperforming asset total was comprised of $55.684 million in loans, $324,000 in repossessed assets, and $6.935 million in other real estate.
Of the $62.943 million in nonperforming assets, $15.811 million or 25% are energy credits, $15.487 million of which are service company credits, and $324,000 are production company credits.
Since December 31, 2019, $2.259 million in other real estate has been put under contract to be sold.
Net charge-offs for the three months ended December 31, 2019 were $1.291 million.
$1.700 million was added to the allowance for credit losses during the quarter-ended December 31, 2019.
The average monthly new loan production for the quarter-ended December 31, 2019 was $496 million.
Loans outstanding at December 31, 2019 were $18.845 million -- excuse me, $18.845 billion.
The December 31, 2019 loan total is made up of 38% fixed rate loans, 34% floating rate, and 28% variable rate loans.

Summary:
Our earnings per diluted common share were $1.01 for three months ending December 31, 2019, compared with the $1.19 for the same period in 2018, and were impacted by merger-related expenses of $46.4 million.