Net loss attributable to common stockholders increased by approximately $10.7 million to $10.9 million for the three months ended June 30, 2023 from $223,000 for the three months ended June 30, 2022. This is a result of the changes discussed above, principally due to the increased net interest expense, amortization of deferred finance costs and increased operating and interest expenses at 77 Greenwich, as well as the gain on the sale of our joint venture in 2022.
Results of Operations for the Six Months Ended June 30, 2023 Compared to the Six Months Ended June 30, 2022
Rental revenues in total increased by approximately $445,000 to $2.9 million for six months ended June 30, 2023 from $2.5 million for the six months ended June 30, 2022. This consisted of an increase in rent revenues of approximately $423,000 to $2.8 million for the six months ended June 30, 2023 from $2.4 million for the six months ended June 30, 2022, as well as an increase in tenant reimbursements of approximately $22,000 to $112,000 for the six months ended June 30, 2023 from $90,000 for the six months ended June 30, 2022. The increase in total rental revenues and its related components was due to higher occupancy, higher base rents and fewer rent concessions at 237 11th during the six months ended June 30, 2023 compared to the six months ended June 30, 2022 due to completion of remediation of the construction related defects.
Other income increased by approximately $118,000 to $144,000 for the six months ended June 30, 2023 from $26,000 for the six months ended June 30, 2022. This increase is due to a contractual payment received as a result of the cancelation of the purchase and sale agreement for the Paramus, New Jersey property in January 2023, as well as a slight increase in the SCA’s construction supervision fee.
Sales of residential condominium units at 77 Greenwich increased by approximately $7.1 million to $18.3 million for the six months ended June 30, 2023 from $11.2 million for the six months ended June 30, 2022. We closed on seven and five residential condominium units during the six months ended June 30, 2023 and 2022, respectively. Units that we closed during 2022 were generally lower priced, smaller units on the building’s lower floors, many of which entered into contract during the height of the pandemic.
Property operating expenses increased by approximately $508,000 to $2.1 million for the six months ended June 30, 2023 from $1.6 million for the six months ended June 30, 2022. The increase was principally due to increased legal expenses associated with the ongoing legal claims against the seller of the property at 237 11th, as well as less capitalized operating costs associated with 77 Greenwich during the six months ended June 30, 2023 compared to the six months ended June 30, 2022. Property operating expenses consisted primarily of expenses incurred for utilities, payroll, COVID-19 related supplies and general operating expenses as well as repairs and maintenance and leasing commission at 237 11th, general operating expenses at 77 Greenwich, including marketing costs, and to a lesser extent expenses related to the Paramus, New Jersey property.
Real estate tax expense increased by approximately $108,000 to $914,000 for the six months ended June 30, 2023 from $806,000 for the six months ended June 30, 2022. This increase was mainly due to less capitalized real estate tax expenses for 77 Greenwich for the six months ended June 30, 2023 as compare to the six months ended June 30, 2022.
General and administrative expenses increased by approximately $274,000 to $3.3 million for the six months ended June 30, 2023 from $3.0 million for the six months ended June 30, 2022. For the six months ended June 30, 2023, approximately $208,000 related to stock-based compensation, $1.3 million related to payroll and payroll related expenses, $869,000 related to other corporate expenses, including board fees, corporate office rent and insurance and $903,000 related to legal, accounting and other professional fees. For the six months ended June 30, 2022, approximately $225,000 related to stock-based compensation, $1.4 million related to payroll and payroll related expenses, $650,000 related to other corporate expenses, including board fees, corporate office rent and insurance and $681,000 related to legal, accounting and other professional fees.
Pension related costs increased by approximately $28,000 to $287,000 for the six months ended June 30, 2023 compared to $315,000 for the six months ended June 30, 2022. These costs represent professional fees and other periodic pension costs incurred in connection with the legacy Syms Pension Plan (see Note 8 – Pension Plan to our consolidated financial statements for further information).
Cost of sales – residential condominium units increased by approximately $7.0 million to $17.5 million for the six months ended June 30, 2023 from $10.5 million for the six months ended June 30, 2022. We closed on seven and five residential condominium units during the six months ended June 30, 2023 and 2022, respectively. Cost of sales consists of