The accompanying unaudited consolidated financial statements have been prepared in accordance with generally accepted accounting principles for interim financial information and the instructions to Form 10-Q and Article 10 of Regulation S-X of the SEC. Accordingly, these do not include all of the information and footnotes required for a fair presentation of financial position, results of operations and cash flows in conformity with GAAP and should be read in conjunction with the Company’s consolidated financial statements and the notes thereto appearing in BKU’s Annual Report on Form 10-K for the year ended December 31, 2019 filed with the SEC. In the opinion of management, all adjustments, consisting of normal recurring adjustments, considered necessary for a fair presentation have been included. Operating results for the three and six months ended March 31,June 30, 2020 are not necessarily indicative of the results that may be expected in future periods. 

Certain amounts presented for prior periods have been reclassified to conform to the current period presentation.

The Company's loan portfolio contains 1-4 single family residential first mortgages, government insured residential mortgages, an insignificant amount of home equity loans and lines of credit and other consumer loans; multi-family, non-owner occupied commercial real estate, construction and land, owner-occupied commercial real estate and commercial and industrial loans, PPP loans, mortgage warehouse lines of credit and sales-type and direct financing leases. Loans are reported at amortized cost basis, net of the ACL.

Interest income is accrued based on the principal amount outstanding. Non-refundable loan origination fees, net of direct costs of originating or acquiring loans, as well as purchase premiums and discounts, are deferred and recognized as adjustments to yield over the contractual lives of the related loans using the level yield method.

Commercial loans are placed on non-accrual status when (i) management has determined that full repayment of all contractual principal and interest is in doubt, or (ii) the loan is past due 90 days or more as to principal or interest unless the loan is well secured and in the process of collection. Residential and other consumer loans, other than government insured residential loans, are generally placed on non-accrual status when they are 90 days past due. When a loan is placed on non-accrual status, uncollected interest accrued is reversed and charged to interest income. Payments received on nonaccrual commercial loans are applied as a reduction of principal. Interest payments are recognized as income on a cash basis on nonaccrual residential loans. Commercial loans are returned to accrual status only after all past due principal and interest has been collected and full repayment of remaining contractual principal and interest is reasonably assured. Residential and consumer loans are generally returned to accrual status when less than 90 days past due. Past due status of loans is determined based on the contractual next payment due date. Loans less than 30 days past due are reported as current.

Contractually delinquent government insured residential loans are not classified as non-accrual due to the nature of the guarantee. Contractually delinquent PCD loans are not classified as non-accrual as long as the Company has a reasonable expectation about amounts expected to be collected.

In certain situations, due to economic or legal reasons related to a borrower's financial difficulties, the Company may grant a concession to the borrower for other than an insignificant period of time that it would not otherwise consider. At that time, the related loan is classified as a TDR. The concessions granted may include rate reductions, principal forgiveness, payment forbearance, extensions of maturity at rates of interest below that commensurate with the risk profile of the loans, modification of payment terms and other actions intended to minimize economic loss. A TDR is generally placed on non-accrual status at the time of the modification unless the borrower was performing prior to the restructuring.

Under recently issued inter-agency and authoritative guidance and consistent with the CARES Act, short-term (generally periods of six months or less) deferrals or modifications related to COVID-19 will typically not be categorized as TDRs.

The Company reviews its AFS debt securities for credit loss impairment at the individual security level on at least a quarterly basis. A security is impaired if its fair value is less than its amortized cost basis. A decline in fair value below amortized cost basis represents a credit loss impairment to the extent the Company does not expect to recover the amortized cost basis of the security. Impairment related to credit losses is recorded through the ACL to the extent fair value is less than the amortized cost basis. Declines in fair value that have not been recorded through the ACL are recorded through other comprehensive income, net of applicable taxes.

In assessing whether an impairment is credit loss related, the Company compares the present value of cash flows expected to be collected to the security's amortized cost basis. If the present value of cash flows expected to be collected is less than the amortized cost basis of the security, a credit loss exists and an ACL is recorded. The Company discounts expected cash flows at the effective interest rate implicit in the security at the purchase date, adjusted for expected prepayments. For floating rate securities, the Company uses the floating rate as it changes over the life of the security. In developing estimates about cash flows expected to be collected and determining whether a credit loss exists, the Company considers information about past events, current conditions and reasonable and supportable forecasts. Factors and information that the Company uses in making its assessments include, but are not necessarily limited to, the following:

The relative importance assigned to each of these factors varies depending on the facts and circumstances pertinent to the individual security being evaluated.

Timely payment of principal and interest on securities issued by the U.S. Government, U.S. government agencies and U.S. government sponsored entities is explicitly or implicitly guaranteed by the U. S. government. Therefore, the Company expects to recover the amortized cost basis of these securities.

If the Company intends to sell a security in an unrealized loss position, or it is more likely than not that the Company will be required to sell the security before recovery of its amortized cost basis, any allowance for credit losses will be written off and the amortized cost basis will be written down to the debt security’s fair value at the reporting date with any incremental impairment reported in earnings.

Historically, the Company has not experienced credit losses related to AFS securities or uncollectible interest on its AFS securities. However, AFS securities would be charged off to the extent that there was no reasonable expectation of recovery of amortized cost basis. AFS securities would be placed on non-accrual status if the Company did not reasonably expect to receive interest payments in the future and interest accrued would be reversed against interest income. Securities would be returned to accrual status only when collection of interest was reasonably assured.

Expected credit losses are estimated on a collective basis for groups of loans that share similar risk characteristics. Factors that may be considered in aggregating loans for this purpose include but are not necessarily limited to, product or collateral type, industry, geography, internal risk rating, credit characteristics such as credit scores or collateral values, and historical or expected credit loss patterns. For loans that do not share similar risk characteristics with other loans such as collateral dependent loans and TDRs, expected credit losses are estimated on an individual basis.

Expected credit losses are estimated over the contractual terms of the loans, adjusted for expected prepayments. Expected prepayments for commercial loans are generally estimated based on the Company's historical experience. For residential loans, expected prepayments are estimated using a model that incorporates industry prepayment data, calibrated to reflect the Company's experience. The contractual term excludes expected extensions, renewals, and modifications unless either of the following applies: management has a reasonable expectation at the reporting date that a TDR will be executed with an individual borrower or the extension or renewal options are included in the original or modified contract at the reporting date and are not unconditionally cancellable by the Company.

The Company has elected a 5-year reasonable and supportable forecast period, with mean reversion occurring within the credit loss models based on the economic inputs. The length of the reasonable and supportable forecast is evaluated at each reporting period and adjusted if deemed necessary. At June 30, 2020, the Company changed from a 5-year to a 2-year reasonable and supportable forecast period in estimating the ACL.

For the substantial majority of portfolio segments and subsegments, including residential loans other than government insured loans, and most commercial and commercial real estate loans, expected losses are estimated using econometric models. The models employ a factor based methodology, leveraging data sets containing extensive historical loss and recovery information by industry, geography, product type, collateral type and obligor characteristics, to estimate PD and LGD. Measures of PD for commercial loans incorporate current conditions through market cycle or credit cycle adjustments. For residential loans, the models consider FICO and adjusted LTVs. PDs and LGDs are then conditioned on the reasonable and supportable economic forecast. Projected PDs and LGDs are applied to estimated exposure at default, considering the term and payment structure of the loan, to generate estimates of expected loss at the loan level. For criticized or classified loans, PDs may be adjusted to industry benchmark PDs appropriate to the current risk rating if the most current financial information available is deemed not to be reflective of the borrowers' current financial condition. These loan level estimates are aggregated to generate a collective estimate for groups of loans that share common risk characteristics.

For certain less material portfolios including loans and leases to state and local government entities originated by Pinnacle, small balance commercial loans and consumer loans, the WARM method is used to estimate expected credit losses. For the Pinnacle portfolio, historical loss information is based on municipal historical default and recovery data, segmented by credit rating. For small balance commercial loans, historical loss information is based on the Company's historical loss experience over a five year period. For consumer loans, historical loss information is based on peer data; this portfolio subsegment is not significant. All loss estimates are conditioned as applicable on changes in current conditions and the reasonable and supportable economic forecast. Expected credit losses for mortgage warehouse lines of credit are estimated based primarily on the Company's historical loss experience, conditioned as applicable on changes in current conditions and the reasonable and supportable economic forecast. Generally, given the nature of these loans, losses would be expected to manifest within a very short time period after origination.

The Company expects to collect the amortized cost basis of government insured residential loans and PPP loans due to the nature of the government guarantee, so the quantitative ACL is zero for these loans.

Qualitative adjustments are made to the ACL when, based on management’s judgment, there are factors impacting expected credit losses not taken into account by the quantitative calculations. Potential qualitative adjustments are categorized as follows:

Collateral dependent loans are those for which the borrower is experiencing financial difficulty and repayment is expected to be provided substantially through the operation or sale of the collateral. These loans do not typically share similar risk characteristics with other loans and expected credit losses are evaluated on an individual basis. Loans evaluated individually are not included in the collective evaluation. Estimates of expected credit losses for collateral dependent loans, whether or not foreclosure is probable, are based on the fair value of the collateral adjusted for selling costs when repayment depends on sale of the collateral.

For TDRs, or loans for which there is a reasonable expectation that a TDR will be executed, that are not collateral dependent, the credit loss estimate is determined by comparing the net present value of expected cash flows, discounted at the loan’s original effective interest rate, to the amortized cost basis of the loan.

Expected credit losses related to off-balance sheet credit exposures are estimated over the contractual period for which the Company is exposed to credit risk via a contractual obligation to extend credit, unless that obligation is unconditionally cancellable by the Company. Expected credit losses are estimated using essentially the same methodologies employed to estimate expected credit losses on the amortized cost basis of loans, taking into consideration the likelihood and amount of additional amounts expected to be funded over the terms of the commitments. The liability for credit losses on off-balance sheet credit exposures is presented within other liabilities on the consolidated balance sheets, distinct from the ACL. Adjustments to the liability are included in the provision for credit losses.

The computation of basic and diluted earnings (loss) per common share is presented below for the periods indicated (in thousands, except share and per share data):

Participating securities include unvested shares and 3,023,314 dividend equivalent rights that were issued in conjunction with the IPO of the Company's common stock. These dividend equivalent rights expire in 2021 and participate in dividends on a one-for-one basis. Participating securities have the right to participate in the earnings of the Company, but no contractual obligation to share in losses. As a result, these securities impacted the calculation of earnings per common share for the three months ended March 31, 2019 but did not impact the calculation of loss per common share for the three months ended March 31, 2020.

Potentially dilutive unvested shares and share units totaling 1,768,7691,743,403 and 1,218,8401,119,641 were outstanding at March 31,June 30, 2020 and 2019, respectively, but excluded from the calculation of diluted earnings (loss) per common share because their inclusion would have been anti-dilutive.

Investment securities held to maturity at March 31,June 30, 2020 and December 31, 2019 consisted of 1 State of Israel bond maturing in 2024. At March 31,June 30, 2020 and December 31, 2019, accrued interest receivable on investments totaled $24$23 million and $28 million, respectively, and is included in other assets in the accompanying consolidated balance sheets.

At March 31,June 30, 2020, contractual maturities of investment securities available for sale, adjusted for anticipated prepayments when applicable, were as follows (in thousands):

The carrying value of securities pledged as collateral for FHLB advances, public deposits, interest rate swaps and to secure borrowing capacity at the FRB totaled $6.8$4.8 billion and $2.4 billion at March 31,June 30, 2020 and December 31, 2019, respectively.

The following tables present the aggregate fair value and the aggregate amount by which amortized cost exceeded fair value for investment securities available for sale in unrealized loss positions aggregated by investment category and length of time that individual securities had been in continuous unrealized loss positions at the dates indicated (in thousands). No ACL was recorded for any investment securities available for sale in an unrealized loss positionsposition at March 31,June 30, 2020.

The Company monitors its investment securities available for sale for credit loss impairment on an individual security basis. No securities were determined to be credit loss impaired during the three and six months ended March 31,June 30, 2020 or other than temporarily impaired during the three and six months ended March 31,June 30, 2019. The Company does not intend to sell securities that are in significant unrealized loss positions at March 31,June 30, 2020 and it is not more likely than not that the Company will be required to sell these securities before recovery of the amortized cost basis, which may be at maturity. In making this determination, the Company considered its current and projected liquidity position, its investment policy as to permissible holdings and concentration limits, regulatory requirements and other relevant factors.

At March 31,June 30, 2020, 314224 securities available for sale were in unrealized loss positions. The amount of impairment related to 2964 of these securities was considered insignificant both individually and in the aggregate, totaling approximately $285$398 thousand and no further analysis with respect to these securities was considered necessary.

Unrealized losses at March 31,June 30, 2020, particularly in the private label CMBS and CLO asset classes, were primarily attributable to widening spreads, resulting in large part from market response to, and dislocation in the wake of, the emerging COVID-19 pandemic.

The basis for concluding that AFS securities were not credit loss impaired and no ACL was considered necessary at March 31,June 30, 2020 is described further discussed below.

At March 31,June 30, 2020, 1 U.S Treasury security, NaN U.S. Government agency and sponsored enterprise residential MBS, 5 U.S. Government agency and sponsored enterprise commercial MBS and 1311 SBA securities were in unrealized loss positions. The timely payment of principal and interest on these securities is explicitly or implicitly guaranteed by the U.S. Government. As such, there is an assumption of zero credit loss and the Company expects to recover the entire amortized cost basis of these securities.