Julie Shamburger
Analyst · KBW
Thank you, Suni. Good morning, everyone, and welcome to Southside Bancshares' Third Quarter 2018 Earnings Call. We are pleased to report a strong third quarter with net income of $20.3 million compared to third quarter 2017 net income of $14.5 million, a 39.9% increase. Our diluted earnings per share for the third quarter ended September 30, 2018, were $0.58 per share, an increase of $0.09 or 18.4% compared to $0.49 per share for the same period last year.
During the third quarter, we reported a net interest margin of 3.14% and a net interest spread at 2.82%, decreases of 5 basis points and 8 basis points, respectively, on a linked-quarter basis. We recorded $478,000 of loan accretion this quarter, a decrease from last quarter and a 3 basis point decrease in the net interest margin for the quarter on a linked-quarter basis. We recorded loan loss provision expense during the third quarter of $975,000, a decrease of $306,000 compared to $1.3 million of provision expense recorded in the previous quarter.
During the 3 months ended September 30, 2018, our noninterest income, excluding net losses on AFS securities, decreased $576,000, a result of less bank-owned life insurance income due to a death benefit recorded last quarter. During the same period, we recorded losses on the sale of available-for-sale securities of $741,000, an increase of $409,000 on a linked-quarter basis.
During the 3 months ended September 30, 2018, our noninterest expense, excluding acquisition and amortization expense, increased $326,000 or 1.2% on a linked-quarter basis, due to the increase in salaries and employee benefits, partially offset by decreases reflected in most of the remaining noninterest expense categories. Last quarter, we reported a decrease in salary and employee benefit expense due to a nonrecurring reversal of a split dollar and postretirement liability associated with the death of a retired executive of approximately $834,000. At this time, we believe fourth quarter salary and employee benefit expense should be consistent with the third quarter. We expect total noninterest expense of approximately $29 million for the fourth quarter.
We continue to maintain cost efficiencies with an efficiency ratio of 48.91% for the 3 months ended September 30, 2018, compared to 47.56% last quarter and 51.28% for the first quarter of 2018. The effective tax rate for the 3 and 9 months ended September 30, 2018, was 9.7% and 11.9%, respectively. We recorded a discrete tax benefit of $800,000 associated with the remeasurement of our deferred taxes in connection with the Tax Cuts and Jobs Act, which lowered our effective tax rate by 3.6% and 1.2%, respectively, for the 3 and 9 months ended September 30, 2018. Excluding the net impact and discrete tax items, our effective tax rate was approximately 13.6% and 13.4% for the 3 and 9 months ended September 30, 2018, respectively. At this time, excluding the net impact of discrete tax items, we are estimating the final effective tax rate for 2018 at approximately 13.4%.
During the third quarter, we experienced a slight increase in total loans of $3.6 million compared to the decrease of $38.7 million reported in the second quarter. Nonperforming assets totaled $39.6 million or 0.65% of total assets at September 30, 2018, a decrease of $2.8 million from June 30, 2018.
Next, I'll give a brief update on our securities portfolio. We further reduced the size of the securities portfolio by $99.6 million during the third quarter...