Unless the context requires otherwise, all references to the "Company," "SL Green," "we," "our" and "us" in this annual report means SL Green Realty Corp., a Maryland corporation, and one or more of its subsidiaries, including the Operating Partnership, or, as the context may require, SL Green only or the Operating Partnership only, and "S.L. Green Properties" means S.L. Green Properties, Inc., a New York corporation, as well as the affiliated partnerships and other entities through which Stephen L. Green historically conducted commercial real estate activities.

In connection with the Company's initial public offering, or IPO, in August 1997, the Operating Partnership received a contribution of interests in real estate properties as well as a 95% economic, non-voting interest in the management, leasing and

Substantially all of our assets are held by, and all of our operations are conducted through, the Operating Partnership. We are the sole managing general partner of the Operating Partnership, and as of December 31, 2020,2021, we owned 94.71%94.59% of its economic interests. All of the management and leasing operations with respect to our wholly-owned properties are conducted through SL Green Management LLC, or Management LLC. The Operating Partnership owns 100% of Management LLC.

In order to maintain the Company's qualification as a REIT while realizing income from management, leasing and construction contracts with third parties and joint venture properties, all of these service operations are conducted through the S.L. Green Management Corp, or the Service Corporation, a consolidated variable interest entity. We, through our Operating Partnership, receive substantially all of the cash flow from the Service Corporation's operations. All of the voting common stock of the Service Corporation is held by an entity owned and controlled by Stephen L. Green, who serves as a member and as the chairman emeritus of the Company's board of directors.

SL Green, is Manhattan's largest owner of office real estate, and an investment-grade, S&P 500 company that is focused primarily on the acquisition, development, repositioning, ownership, management, operation and value maximizationoperation of Manhattan commercial properties, principally office properties.

Our core business is the ownership of high quality commercial properties and our primary business objective is to maximize the total return to stockholders, through net income attributable to common stockholders and funds from operations, or FFO, and through asset value appreciation. The commercial real estate expertise resulting from owning, operating, investing, developing, redeveloping and lending on real estate in Manhattan for over 40 years has enabled us to invest in a collection of premier office properties, selected retail and multifamily residential assets, and high-quality debt and preferred equity investments.

We are led by a strong, experienced management team that provides a foundation of skills in all aspects of real estate, including acquisitions, dispositions, management, leasing, development, redevelopment, and financing.estate. It is with this team that we have achieved a market leading position in our targeted submarkets.

We seek to enhance the value of our company by executing strategies that include the following:

We seek to capitalize on our management's extensive knowledge of Manhattan and the New York metropolitan area and the needs of our tenants through proactive leasing and management programs, which include: (i) use of in-depth market experience resulting from managing and leasing tens of millions of square feet of office, retail and residential space since the Company was founded; (ii) careful tenant management, which results in a high tenant retention rate, long average lease terms and a manageable lease expiration schedule; (iii) utilization of an extensive network of third-party brokers to supplement our in-house leasing team; (iv) use of comprehensive building management analysis and planning; and (v) a commitment to tenant satisfaction by understanding and appreciating our tenant's businesses and the environment in which they are operating, while providing high quality tenant services at competitive rental rates.

We acquire properties for long-term value appreciation and earnings growth. This strategy has resulted in capital gains that increase our investment capital base. In implementing this strategy, we continually evaluate potential acquisition opportunities. These opportunities may come from new properties as well as the acquisition of properties in which we already hold a joint venture interest or, from time to time, from our debt and preferred equity investments.

Through intimate knowledge of our marketsmarket, we have developed an ability to source transactions with superior risk-adjusted returns by capturing off-market opportunities. In rising markets, we primarily seek to acquire strategic vacancies that provide the opportunity to take advantage of our exceptional leasing and repositioning capabilities to increase cash flow and property value. In stable or falling markets, we primarily target assets featuring credit tenancies with fully escalated in-place rents to provide cash flow stability near-term and the opportunity for increases over time.

We continually evaluate our portfolio to identify those properties that are most likely to meet our long-term earnings and cash flow growth objectives and contribute to increasing portfolio value. Properties that no longer meet our objectives are evaluated for sale or in certain cases, joint venture, to release equity created through management's value enhancement programs or to take advantage of attractive market valuations.

We seek to efficiently deploy the capital proceeds generated from these dispositions into other property acquisitions, anddevelopment or redevelopment projects or debt and preferred equity investments that we expect will provide enhanced future capital gains and earnings growth opportunities. Management may also elect to utilize the capital proceeds from these dispositions to repurchase shares of our common stock, repay existing indebtedness of the Company or its subsidiaries, or increase cash liquidity.

Our extensive knowledge of the marketsmarket in which we operate and our ability to efficiently plan and execute capital projects provide the expertise to enhance returns by repositioning properties that are underperforming. Many of the properties we own or seek to acquire feature unique architectural design elements or other amenities and characteristics that can be appealing to tenants when fully exploited. Our strategic investment in these properties, combined with our active management and pro-active leasing, provide the opportunity to creatively meet market needs and generate favorable returns.

Our constant interactions with tenants and other market participants keep us abreast of innovations in workplace layout, store design and smart living. We leverage this information to identify properties primed for development or redevelopment to meet these demands and unlock value. The expertise and relationships that we have built from managing complex construction projects in New York City and its surrounding areas allow us to cost efficiently add new and renovated assets of the highest quality and desirability to our operating portfolio.

We invest in well-collateralized debt and preferred equity investments in the markets in which we operate, primarilyprincipally New York City, that generate attractive yields. See Note 5, "Debt and Preferred Equity Investments," in the accompanying consolidated financial statements. Knowledge of our markets and our leasing and asset management expertise provide underwriting capabilities that enable a highly educated assessment of risk and return. The benefits of this investment program, which has a carefully managed aggregate size, include the following:

Our objective is to maintain multiple sources of efficient corporate and property level capital to obtain the most appropriate and lowest cost of capital. This objective is supported by:

Manhattan is the largest office market in the United States containing more rentable square feet than the next four largest central business district office markets combined. According to Cushman and Wakefield Research Services as of December 31, 2020,2021, Manhattan has a total office inventory of approximately 404.7408.3 million square feet, including approximately 248.6250.6 million square feet in midtown. The properties in our portfolio are primarily concentrated in some of Manhattan's most prominent midtown locations.

While the near-term addition of new supply to the Manhattan office inventory is expected to be nominal relative to the size of the overall market, we view new supply in locations near a variety of transportation options as a positive to the Manhattan office market given the older vintage of the majority of Manhattan’s office inventory and the increasing desire of certain tenants to occupy new, high quality, efficient office space which often isn’t availablethat provides for easy commutability for their employees.

Leasing activity in older vintage properties.

Leases entered into for space in Manhattan typically contain terms that may not be contained in leases in other U.S. office markets. The initial term of leases entered into for space in Manhattan is generally seven to fifteen years. Tenants leasing space in excess of 10,000 square feet for an initial term of 10 years or longer often will negotiate an option to extend the term of the lease for one or two renewal periods, typically for a term of five years each. The base rent during the initial term often will provide for agreed-upon periodic increases over the term of the lease. Base rent for renewal terms is most often based upon the then fair market rental value of the premises as of the commencement date of the applicable renewal term (generally determined by binding arbitration in the event the landlord and the tenant are unable to mutually agree upon the fair market value), though base rent for a renewal period may be set at 95% of the then fair market rent. Very infrequently, leases may contain termination options whereby a tenant can terminate the lease obligation before the lease expiration date uponwith payment of a penalty together with repayment of the unamortized portion of the landlord's transaction costs (e.g., brokerage commissions, free rent periods, tenant improvement allowances, etc.).

In addition to base rent, a tenant will generally also pay its pro rata share of increases in real estate taxes and operating expenses for the building over a base year, which is typically the year during which the term of the lease commences, based upon the tenant's proportionate occupancy of the building. In some smaller leases (generally less than 10,000 square feet), in lieu of paying additional rent based upon increases in building operating expenses, base rent will be increased each year during the lease term by a set percentage on a compounding basis (though the tenant will still pay its pro rata share of increases in real estate taxes over a base year).

Tenants typically receive a free rent period following commencement of the lease term, which in some cases may coincide with the tenant's construction period.

The landlord most often supplies electricity either on a sub-metered basis at the landlord's cost plus a fixed percentage or on a rent inclusion basis (i.e., a fixed fee is added to the base rent for electricity, which amount may increase based upon increases in electricity rates or increases in electrical usage by the tenant). Base building services, other than electricity, such as heat, air conditioning, freight elevator service during business hours and base building cleaning typically are provided at no additional cost, but are included in the building's operating expenses. The tenant will typically pay additional rentamounts only for services whichthat exceed base building services or for services whichthat are provided other than during normal business hours.

In a typical lease for a new tenant renting in excess of 10,000 square feet, the landlord will deliver the premises with existing improvements demolished. In such instances, the landlord will typically provide a tenant improvement allowance, which is a fixed sum that the landlord makes available to the tenant to reimburse the tenant for all or a portion of the tenant's initial construction of its premises. Such sum typically is payable as work progresses, upon submission by the tenant of invoices for the cost of construction and lien waivers. However, in certain leases (most often for relatively small amounts of space), the landlord will construct the premises for the tenant at a cost to the landlord not to exceed an agreed upon amount with the tenant paying any amount in excess of the agreed upon amount. In addition, landlords may rent space to a tenant that is "pre-built" (i.e., space that was constructed by the landlord in advance of lease signing and is ready to for the tenant to move in with the tenant selecting paint and carpet colors).

The following table sets forth the weighted average occupancy rates at our office properties based on space leased for properties owned by us as of December 31, 2020:2021:

We are constantly evaluating our schedule of future lease expirations to mitigate occupancy risk while maximizing net effective rents. We proactively manage future lease expirations based on our view of estimated current and future market conditions and asking rents. The following table sets forth our future lease expirations, excluding triple net leases, and management's estimates of market asking rents. Taking rents are typically lower than asking rents and may vary from building to building. There can be no assurances that our estimates of market rents are accurate or that market rents currently prevailing will not erode or outperform in the future.

The Company is a REIT that is engaged in the acquisition, development, repositioning, ownership, management and operation of commercial and residential real estate properties, principally office properties, located in the New York metropolitan area, principally Manhattan, and has two reportable segments: real estate and debt and preferred equity investments. Our industry segments are discussed in Note 21, "Segment Information," in the accompanying consolidated financial statements.

AtAs of December 31, 2020,2021, our real estate portfolio was primarilyprincipally located in one geographical market, theManhattan, a borough of New York metropolitan area.City. The Company's primary sources of real estate revenue are generated from tenant rents, escalations and reimbursement revenue. Real estate property operating expenses consist primarily of cleaning, security, maintenance, utility costs, real estate taxes and, at certain properties, ground rent expense. As of December 31, 2020,2021, one tenant in our office portfolio, ViacomCBS Inc., contributed 5.7%6.3% of our share of annualized cash rent. No other tenant contributed more than 5.0% of our share of annualized cash rent. No property contributed in excess of 10.0% of our consolidated total revenue for 2020.2021.

AtAs of December 31, 2020,2021, we held debt and preferred equity investments with a book value of $1.1 billion, excluding $0.1 billion$10.1 million of debt and preferred equity investments and other financing receivables that are included in balance sheet line items other than the Debt and Preferred Equity Investmentspreferred equity investments line item. AtAs of December 31, 2020,2021, the assets underlying our debt and preferred equity investments were located in the New York metropolitan area.City. The primary sources of debt and preferred equity revenue are generated from interest and fee income.

Our employees are our most important asset. As we navigated through the challenges of the COVID-19 pandemic, we implemented new employee programs and physical office space enhancements to keep employees healthy, safe, and focused. Through the commitment of our employees, we have remained fully operational for all tenants, including the essential businesses that fill our buildings. As a result of strategic changes to our corporate headquarters, along with employee-focused programs guided by employee input,buildings, and we were among the first employeremployers in New York City to be able to return 100% of itsour employees to the office.office in June 2020.

We are dedicated to creating a diverse workplace where employees feel valued and accepted regardless of race, color, religion, national origin, gender, sexual orientation, age, disability, or veteran status. We have a dual-track performance management program, which includes both ongoing goal setting and annual performance reviews for all employees. Communication, teamwork, and collaboration are the fundamental attributes that are the foundation of our company culture. We promote the professional development of our employees by offering opportunities to participate in trainings and continuing

Our compensation program is designed to incentivize employees by offering competitive compensation comprised of fixed and variable pay including base salaries and cash bonuses. SeveralMany of our employees also receive equity awards that are subject to vesting over a multi-year period based on continued service. We believe these equity awards serve as an additional retention tool for our employees. By cultivating a work culture that prioritizes our people through training, diversity, education, and volunteerism, we have been able to retain a long-tenured staff with 61%50% of current employees remaining on board forhaving a tenure of five years or more.more and a management team that has an average tenure of 19.3 years.

AtAs of December 31, 2020,2021, we employed 794931 employees, 273334 of whom were employed in our corporate offices. There are currently sixfive collective bargaining agreements which cover the union workforce that services substantially all of our properties.

TheA significant majority of our property holdings are comprised of commercial office properties located in midtown Manhattan. Our property holdings also include some retail properties and multifamily residential properties. As a result of the concentration of our holdings, our business is dependent on the condition of the New York metropolitan area economy in general and the market for office space in midtown Manhattan in particular. Future weakness and uncertainty in the New York metropolitan area economy could materially reduce the value of our real estate portfolio and our rental revenues, and thus adversely affect our cash flow and our ability to service currentour debt obligations and to pay dividends and distributions to security holders.

If tenants decide not to renew their leases upon expiration, we may not be able to relet the space. Even if tenants do renew or we can relet the space, the terms of a renewal or new lease, taking into account among other things, the cost of improvements to the property and leasing commissions, may be less favorable than the terms in the expired leases. As of December 31, 2020,2021, approximately 35.3%38.0% of the rentable square feet at our consolidated properties and approximately 30.6%29.3% of the rentable square feet at our unconsolidated joint venture properties are scheduled to expire by December 31, 2025.2026. As of December 31, 2020,2021, these leases had annualized escalated rent totaling $253.7$242.7 million and $330.9$428.9 million, respectively. In addition, changes in space utilization by tenants may cause us to incur substantial costs in renovating or redesigning the internal configuration of the relevant property in order to renew or relet space. If we are unable to promptly renew the leases or relet the space at similar rates or if we incur substantial costs in renewing or reletting the space, our cash flow and ability to service our debt obligations and pay dividends and distributions to security holders could be adversely affected.

The leasing of real estate is highly competitive. The principal competitive factors are rent, location, lease term, lease concessions, services provided and the nature and condition of the property to be leased. We directly compete with all owners, developers and operators of similar space in the areas in which our properties are located.

Our commercial office properties are concentrated in highly developed areas of the New York metropolitan area. Manhattan is the largest office market in the United States. The number of competitive office properties in the New York metropolitan area, which may be newer or better located than our properties, could have a material adverse effect on our ability to lease office space at our properties, and on the effective rents we are able to charge.

Our interests in certain properties are entirely or partially comprised of either long-term leasehold or operating sublease interests in the land and the improvements, rather than by ownership of fee interest in the land. As of December 31, 2020,2021, the expiration dates of these long-term leases range from 2043 to 2119, including the effect of our unilateral extension rights at each of these properties. Pursuant to the leasehold arrangements, we, as tenant under the long-term leasehold or the operating sublease, perform the functions traditionally performed by landlords with respect to our subtenants. We are responsible for not only collecting rent from our subtenants, but also maintaining the property and paying expenses relating to the property. Annualized cash rents, including our share of joint venture annualized cash rents, from properties held through long-term leases or operating sublease interests atas of December 31, 20202021 totaled $318.1$281.9 million, or 24.8%22.8%, of our share of total Portfolio annualized cash rent. Unless we purchase a fee interest in the underlying land or extend the terms of these leases prior to expiration, we will no longer operate these properties upon expiration of the leases, which could adversely affect our financial condition and results of operations. Rent payments under leasehold or operating sublease interests are adjusted, within the parameters of the contractual arrangements, at certain intervals. Rent adjustments may result in higher rents that could adversely affect our financial condition and results of operation.

Five of our properties, 1185One Vanderbilt Avenue, of the Americas, 11 Madison Avenue, 420 Lexington Avenue, 1515 Broadway, and 220 East 42nd Street1185 Avenue of the Americas accounted for 35.1%39.0% of our Portfolio annualized cash rent, which includes our share of joint venture annualized cash rent, as of December 31, 2020.2021.

Our revenue and cash available to service debt obligations and for distribution to our stockholders would be materially adversely affected if any of these properties were materially damaged or destroyed. Additionally, our revenue and cash available to service debt obligations and for distribution to our stockholders would be materially adversely affected if tenants at these properties fail to timely make rental payments due to adverse financial conditions or otherwise, default under their leases or file for bankruptcy or become insolvent.

Giving effect to leases in effect as of December 31, 20202021 for consolidated properties and unconsolidated joint venture properties, as of that date, our five largest tenants, based on annualized cash rent, accounted for 16.0%16.5% of our share of Portfolio annualized cash rent, with one tenant, Viacom CBS, Inc., accounting for 5.6%6.3% of our share of Portfolio annualized cash rent, respectively.rent. Our business and results of operations would be adversely affected if any of our major tenants became insolvent, declared bankruptcy, or otherwise refused to pay rent in a timely fashion or at all. In addition, if business conditions in the industries in which our tenants are concentrated deteriorate, or economic volatility has a disproportionate impact on our tenants, we may experience increases in past due accounts, defaults, lower occupancy and reduced effective rents across tenants in such industries, which could in turn have an adverse effect on our business and results of operations.

The Company's development projects are subject to internal and external factors which may affect construction progress. Unforeseen matters could delay completion, result in increased costs or otherwise have a material effect on our results of operations. In addition, the extended time frame to complete these projects could cause them to be subject to shifts and trends in the real estate market which may not be consistent with our current business plans for the properties.

Our business may be affected by volatility in the financial and credit markets and other market, economic, or political challenges experienced by the U.S. economy or the real estate industry as a whole, including changes in law and policy and uncertainty in connection with any such changes. Future periods of economic weakness or volatility could result in reduced access to credit and/or wider credit spreads. Economic or political uncertainty, including concern about growth and the stability of the markets generally and changes in the federal interest rates, may lead many lenders and institutional investors to reduce and, in some cases, cease to provide funding to borrowers, which could adversely affect our liquidity and financial condition, and the liquidity and financial condition of our tenants. Specifically, our business may be affected by the following conditions:

Some of the tenants in our properties are smaller, growth-oriented businesses that may not have the financial strength of larger corporate tenants. Smaller companies generally experience a higher rate of failure than larger businesses. Growth-oriented firms may also seek other office space as they develop. Leasing office space to these companies could createcreates a higher risk of tenant defaults, turnover and bankruptcies, which could adversely affect our cash flow and results of operations.

We earn a significant portion of our income from renting our properties. Our operating costs, however, do not necessarily fluctuate in direct proportion to changes in our rental revenue. If revenues decline more than expenses, we may be forced to borrow to cover our costs, we may incur losses or we may not have cash available to service our debt obligations and to pay dividends and distributions to security holders.

We may acquire properties when we are presented with attractive opportunities. We may face competition for acquisition opportunities from other investors, particularly those investors who are willing to incur more leverage, and this competition may adversely affect us by subjecting us to the following risks:

If we are unable to successfully acquire additional properties, our ability to grow our business could be adversely affected.

Our acquisition activities may not be successful if we are unable to meet required closing conditions or unable to finance acquisitions and developments of properties on favorable terms or at all. Additionally, we have less visibility into the future performance of acquired properties than properties that we have owned for a period of time, and therefore, recently acquired properties may not be as profitable as our existing portfolio.

Further, we may acquire properties subject to both known and unknown liabilities and without any recourse, or with only limited recourse to the seller. As a result, if a liability were asserted against us arising from our ownership of those properties, we might have to pay substantial sums to settle it, which could adversely affect our cash flow. Unknown liabilities with respect to properties acquired might include:

In connection with past and future acquisitions of interests in properties, we have or may agree to restrictions on our ability to sell or refinance the acquired properties for certain periods. These limitations could result in us holding properties which we would otherwise sell, or prevent us from paying down or refinancing existing indebtedness, any of which may have adverse consequences on our business and result in a material adverse effect on our financial condition and results of operations.

We maintain “all-risk” property and rental value coverage (including coverage regarding the perils of flood, earthquake and terrorism, excluding nuclear, biological, chemical, and radiological terrorism ("NBCR")) within three property insurance programs and liability insurance. Separate property and liability coverage may be purchased on a stand-alone basis for certain assets, such as the development of One Vanderbilt.projects. Additionally, one of our captive insurance companies, Belmont Insurance Company, or Belmont, provides coverage for NBCR terrorist acts above a specified trigger. Belmont's retention is reinsured by our other captive insurance company, Ticonderoga Insurance Company ("Ticonderoga"). If Belmont or Ticonderoga are required to pay a claim under our insurance policies, we would ultimately record the loss to the extent of required payments. There is no assurance that in the future we will be able to procure coverage at a reasonable cost. Further, if we experience losses that are uninsured or that exceed policy limits, we could lose the capital invested in the damaged properties as well as the anticipated future cash flows from those properties. Additionally, our debt instruments contain customary covenants requiring us to maintain insurance and we could default under our debt instruments if the cost and/or availability of certain types of insurance make it impractical or impossible to comply with such covenants relating to insurance. Belmont and Ticonderoga provide coverage solely on properties owned, in whole or in part, by the Company or its affiliates.

Furthermore, with respect to certain of our properties, including certain properties held by joint ventures or subject to triple net leases, insurance coverage is obtained by a third-party and we do not control the coverage. While we may have agreements with such third parties to maintain adequate coverage and we monitor these policies, such coverage ultimately may not be maintained or adequately cover our risk of loss.

Our operations are primarily concentrated in the New York metropolitan area. In the aftermath of a terrorist attack or other acts of terrorism or war, tenants in the New York metropolitan area may choose to relocate their business to less populated, lower-profile areas of the United States that those tenants believe are not as likely to be targets of future terrorist activity. In addition, economic activity could decline as a result of terrorist attacks or other acts of terrorism or war, or the perceived threat of such acts. Each of these impacts could in turn trigger a decrease in the demand for space in the New York metropolitan area, which could increase vacancies in our properties and force us to lease our properties on less favorable terms. While under the Terrorism Risk Insurance Program Reauthorization Act of 2019, insurers must make terrorism insurance available under their property and casualty insurance policies, this legislation does not regulate the pricing of such insurance. The absence of affordable terrorism insurance coverage may adversely affect the general real estate lending market, lending volume and the market's overall liquidity and, in the event of an uninsured loss, we could lose all or a portion of our assets. Furthermore, we may also experience increased costs in relation to security equipment and personnel. As a result, the value of our properties and our results of operations could materially decline.

We are subject to risks associated with natural disasters and the effects of climate change, which can include storms, hurricanes and flooding, any of which could have a material adverse effect on our properties, operations and business. To the extent climate change causes changes in weather patterns, our markets could experience increases in storm intensity and rising sea-levels. Over time, these conditions could result in declining demand for office space in our buildings or theour inability of us to operate the buildings at all. Climate change may also have indirect effects on our business by increasing the cost of (or making unavailable) property insurance on terms we find acceptable, increasing the cost of energy at our properties and requiring us to expend funds as we seek to repair and protect our properties against such risks. ClimateAny of these direct or indirect effects of climate change may have a material adverse effect on our properties, operations or business.

There is a potential conflict of interest relating to the disposition of certain property contributed to us by Stephen L. Green and affiliated entities in our initial public offering. Mr. Green serves as a member and as the chairman emeritus of our boardBoard of directors.Directors. If we sell a property in a transaction in which a taxable gain is recognized, for tax purposes the built-in gain would be allocated solely to him and not to us. As a result, Mr. Green has a conflict of interest if the sale of a property he contributed is in our best interest but not his.

In addition, Mr. Green's tax basis includes his share of debt, including mortgage indebtedness, owed by the Operating Partnership. If the Operating Partnership were to retire such debt, then he would experience a decrease in his share of liabilities, which, for tax purposes, would be treated as a distribution of cash to him. To the extent the deemed distribution of cash exceeded his tax basis, he would recognize gain. As a result, Mr. Green has a conflict of interest if the refinancing of indebtedness is in our best interest but not his.

Alliance Building Services, or Alliance, and its affiliates are partially owned by Gary Green, a son of Stephen L. Green, who serves as a member and as the chairman emeritus of our board of directors, and provide services to certain properties owned by us. Alliance’s affiliates include First Quality Maintenance, L.P., or First Quality, Classic Security LLC, Bright Star Couriers LLC and Onyx Restoration Works, and provide cleaning, extermination, security, messenger, and restoration services, respectively. In addition, First Quality has the non-exclusive opportunity to provide cleaning and related services to individual tenants at our properties on a basis separately negotiated with any tenant seeking such additional services. The Service Corporation has entered into an arrangement with Alliance whereby it will receive a profit participation above a certain threshold for services provided by Alliance to certain tenants at certain buildings above the base services specified in their lease agreements.

Our company and our tenants accounted for 15.01%18.80% of Alliance's 20202021 estimated total revenue, based on information provided to us by Alliance. While we believe that the contracts pursuant to which these services are provided were the result of arm's length negotiations, there can be no assurance that the terms of such agreements, or dealings between the parties during the performance of such agreements, will be as favorable to us as those which could be obtained from unaffiliated third parties providing comparable services under similar circumstances.

Cash flow could be insufficient to meet the payments of principal and interest required under our current mortgages, our 20172021 credit facility, our senior unsecured notes, our debentures and indebtedness outstanding at our joint venture properties. The total principal amount of our outstanding consolidated indebtedness was $5.0$4.1 billion as of December 31, 2020,2021, consisting of $1.5$1.3 billion in unsecured bank term loans (or "Term Loan A" and "Term Loan B"), $1.3$0.9 billion under our senior unsecured notes, $0.1 billion of junior subordinated deferrable interest debentures, $2.0$1.4 billion of non-recourse mortgages and loans payable on certain of our properties and debt and preferred equity investments, $110.0$390.0 million drawn under our revolving credit facility, and $26.0$2.0 million of outstanding letters of credit. In addition, we could increase the amount of our outstanding consolidated indebtedness in the future, in part by borrowing under the revolving credit facility portion of our 20172021 credit facility. As of December 31, 2020,2021, the total principal amount of non-recourse indebtedness outstanding at the joint venture

If we are unable to make payments under our 20172021 credit facility, all amounts due and owing at such time shall accrue interest at a per annum rate equal to 2% higher than the rate applicable immediately prior to the default. If we are unable to make payments under our senior unsecured notes, the principal and unpaid interest will become immediately payable. If a property is mortgaged to secure payment of indebtedness and we are unable to meet mortgage payments, the mortgagee could foreclose on the property, resulting in loss of income and asset value. Foreclosure on mortgaged properties or an inability to make payments under our 20172021 credit facility or our senior unsecured notes could trigger defaults under the terms of our other financings, making such financings at risk of being declared immediately payable, and would have a negative impact on our financial condition and results of operations.

The mortgages and mezzanine loans on our properties generally contain customary negative covenants that limit our ability to further mortgage the properties, to enter into material leases without lender consent or materially modify existing leases, among other things. In addition, our 20172021 credit facility and senior unsecured notes contain restrictions and requirements on our method of operations. Our 20172021 credit facility and our unsecured notes also require us to maintain designated ratios, including but not limited to, total debt-to-assets, debt service coverage and unencumbered assets-to-unsecured debt. These restrictions could adversely affect operations (including reducing our flexibility and our ability to incur additional debt), our ability to pay debt obligations and our ability to pay dividends and distributions to security holders.

Advances under our 20172021 credit facility and certain property-level mortgage debt bear interest at a variable rate. Our consolidated variable rate borrowings totaled $1.8$0.8 billion atas of December 31, 2020.2021. In addition, we could increase the amount of our outstanding variable rate debt in the future, in part by borrowing additional amounts under our 20172021 credit facility. Borrowings under our revolving credit facility and term loans bore interest at the 30-day LIBOR,adjusted term SOFR plus 10 basis points, and the applicable spreads of 10085 basis points, 11095 basis points, and 100 basis points, respectively, atas of December 31, 2020.2021. As of December 31, 2020,2021, borrowings under our term loans and junior subordinated deferrable interest debentures totaled $1.5$1.3 billion and $100.0 million, respectively. We may incur indebtedness in the future that also bears interest at a variable rate or may be required to refinance our debt at higher rates. AtAs of December 31, 2020,2021, a hypothetical 100 basis point increase in interest rates across each of our variable interest rate instruments, including our variable rate debt and preferred equity investments which mitigate our exposure to interest rate changes, would increase our net annual interest costs by $14.0$4.8 million and would increase our share of joint venture annual interest costs by $20.6$13.8 million. Our joint ventures may also incur variable rate debt and face similar risks. Accordingly, increases in interest rates could adversely affect our results of operations and financial conditions and our ability to continue to pay dividends and distributions to security holders.

The chief executive of the United Kingdom Financial Conduct Authority ("FCA"), which regulates LIBOR, has announced that the FCA intends to stop compelling banks to submit rates for the calculation of certain LIBOR after 2021. In November 2020,March 2021, ICE Benchmark Administration, the administrator of LIBOR, with the support of the Federal Reserve Board and the FCA, announced plans to extend the publication of certain USD LIBOR settings until June 30, 2023.2023 after which LIBOR reference rates will cease to be provided. It is not possible to predict the effect of these changes or the establishment of alternative reference rates.

The Alternative Reference Rate Committee ("ARRC"), a committee convened by the Federal Reserve that includes major market participants, and on which the SEC staff and other regulators participate, has proposed an alternative rate, the Secured Overnight Financing Rate (“SOFR”), to replace U.S. Dollar LIBOR. Any changes announced by the FCA, ARRC, other regulators or any other successor governance or oversight body, or future changes adopted by such body, in the method pursuant to which U.S. Dollar LIBOR, SOFR, or any other alternative rates are determined may result in a sudden or prolonged

The interest rate hedge instruments we use to manage some of our exposure to interest rate volatility involve risk and counterparties may fail to perform under these arrangements. In addition, these arrangements may not be effective in reducing our exposure to interest rate changes and whenchanges. When existing interest rate hedges terminate, we may incur increased costs in putting in place further interest rate hedges. Failure to hedge effectively against interest rate changes may adversely affect our results of operations.

Our organizational documents do not contain any limitation on the amount of indebtedness we may incur. We consider many factors when making decisions regarding the incurrence of indebtedness, such as the purchase price of properties to be acquired with debt financing, the estimated market value of our properties and the ability of particular properties and our business as a whole to generate cash flow to cover expected debt service. Any changes that increase our leverage could be viewed negatively by investors. Asinvestors and could have a result,material effect on our stockfinancial condition, results of operations, cash flows, the trading price could decrease.of our securities and our ability to pay dividends and distributions to security holders.

Our credit rating and the credit ratings assigned to our debt securities and our preferred stock could change based upon, among other things, our results of operations and financial condition. These ratings are subject to ongoing evaluation by credit rating agencies, and any rating could be changed or withdrawn by a rating agency in the future if, in its judgment, circumstances warrant such action. If any of the credit rating agencies that have rated our securities downgrades or lowers its credit rating, or if any credit rating agency indicates that it has placed any such rating on a “watch list” for a possible downgrading or lowering, or otherwise indicates that its outlook for that rating is negative, such action could have a material adverse effect on our costs and availability of funding, which could in turn have a material adverse effect on our financial condition, results of operations, cash flows, the trading price of our securities and our ability to satisfy our debt service obligations and to pay dividends and distributions to security holders.

We held first mortgages, mezzanine loans, junior participations and preferred equity interests with an aggregate net book value of $1.1 billion atas of December 31, 2020.2021. Some of these instruments may have some recourse to their sponsors, while others are limited to the collateral securing the loan. In the event of a default under these obligations, we may have to take possession of the collateral securing these interests. Borrowers may contest enforcement of foreclosure or other remedies, seek bankruptcy protection against such enforcement and/or bring claims for lender liability in response to actions to enforce their obligations to us. Declines in the value of the property may prevent us from realizing an amount equal to our investment upon foreclosure or realization even if we make substantial improvements or repairs to the underlying real estate in order to maximize such property's investment potential. In addition, we may invest in mortgage-backed securities and other marketable securities.

Our debt and preferred equity investments are carried at the net amounts expected to be collected. We maintain and regularly evaluate the need for reserves to protect against potential future credit losses. Our reserves reflect management's judgment of the probability and severity of losses and the value of the underlying collateral. We cannot be certain that our judgment will prove to be correct and that our reserves will be adequate over time to protect against future credit losses because of unanticipated adverse changes in the economy or events adversely affecting specific properties, assets, tenants, borrowers, industries in which our tenants and borrowers operate or markets in which our tenants and borrowers or their properties are

We co-invest with third parties through partnerships, joint ventures, co-tenancies or other structures, and by acquiring non-controlling interests in, or sharing responsibility for managing the affairs of, a property, partnership, joint venture, co-tenancy or other entity. Therefore, we may not be in a position to exercise sole decision-making authority regarding such property, partnership, joint venture or other entity. Investments in partnerships, joint ventures, or other entities may involve risks not present were a third party not involved, including the possibility that our partners, co-tenants or co-venturers might become bankruptfile for bankruptcy protection or otherwise fail to fund their share of required capital contributions. Additionally, our partners or co-venturers might at any time have economic or other business interests or goals which are competitive or inconsistent with our business interests or goals. These investments may also have the potential risk of impasses on decisions such as a sale, because neither we, nor the partner, co-tenant or co-venturer would have full control over the partnership or joint venture. In addition,

Each of our joint venture agreements has been individually negotiated with our partner in the joint venture and, in some cases, we have agreed to terms that are more favorable to our partner in the joint venture than to us. For example, our partner may be entitled to a specified portion of the profits of the joint venture before we are entitled to any portion of such profits. We may also enter into similar arrangements in the future.

We need a substantial amount of capital to operate and grow our business. This need is exacerbated by the distribution requirements imposed on us for SL Green to qualify as a REIT. We therefore rely on third-party sources of capital, which may not be available on favorable terms or at all. Our access to third-party sources of capital depends on a number of things, including the market's perception of our growth potential and our current and potential future earnings. In addition, we may raise money in the public equity and debt markets and our ability to do so will depend upon the general conditions prevailing in these markets. At any time, conditions may exist which effectively prevent us, or REITs in general, from accessing these markets. Moreover, additional equity offerings may result in substantial dilution of our stockholders' interests, and additional debt financing may substantially increase our leverage.

Substantially all of our assets are held through subsidiaries of our Operating Partnership. Our Operating Partnership’s cash flow isWe are, therefore, dependent on cash distributions from itsthe results of operations of our subsidiaries and their ability to provide us with cash, whether in turn, substantially allthe form of our cash flow is dependent on cash distributions fromdividends paid through our Operating Partnership. The creditors of each ofPartnership, loans or otherwise, to meet our directobligations and indirectto pay any dividends to our equity holders. Any distributions to us from those subsidiaries are entitled to payment of that subsidiary’s obligations to them, when due and payable, before distributions may be made by that subsidiarysubject to its equity holders.

In addition, our participation in any distribution of the assets of any of our direct or indirect subsidiaries upon any liquidation, reorganization or insolvency is only after the claims of the creditors, including trade creditors and preferred security holders, are satisfied.

A change of control of our company could benefit stockholders by providing them with a premium over the then-prevailing market price of our stock. However, provisions contained in our charter and bylaws may delay or prevent a change in control of our company. These provisions, discussed more fully below, are:

To remain qualified as a REIT for federal income tax purposes, not more than 50% in value of our outstanding capital stock may be owned by five or fewer individuals at any time during the last half of any taxable year. For this purpose, stock may be "owned" directly, as well as indirectly under certain constructive ownership rules, including, for example, rules that attribute stock held by one shareholder to another shareholder. In part to avoid violating this rule regarding stock ownership limitations and maintain our REIT qualification, our charter prohibits direct or indirect ownership by any single stockholder of more than 9.0% in value or number of shares of our common stock. Limitations on the ownership of preferred stock may also be imposed by us.

Our board of directors has the discretion to raise or waive this limitation on ownership for any stockholder if deemed to be in our best interest. Our board of directors has granted such waivers from time to time. To obtain a waiver, a stockholder must present the board and our tax counsel with evidence that ownership in excess of this limit will not affect our present or future REIT status.

Absent any exemption or waiver, stock acquired or held in excess of the limit on ownership will be transferred to a trust for the exclusive benefit of a designated charitable beneficiary, and the stockholder's rights to distributions and to vote would terminate. The stockholder would be entitled to receive, from the proceeds of any subsequent sale of the shares transferred to the charitable trust, the lesser of: the price paid for the stock or, if the owner did not pay for the stock, the market price of the stock on the date of the event causing the stock to be transferred to the charitable trust; and the amount realized from the sale.

This limitation on ownership of stock could delay or prevent a change in control of our company.

Under the Maryland General Corporation Law, or the MGCL, "business combinations" between a Maryland corporation and an interested stockholder or an affiliate of an interested stockholder are prohibited for five years after the most recent date on which the interested stockholder becomes an interested stockholder. These business combinations include a merger, consolidation, share exchange or, in circumstances specified in the statute, an asset transfer or issuance or reclassification of equity securities. An interested stockholder is defined as:

A person is not an interested stockholder under the statute if the board of directors approves in advance the transaction by which he otherwise would have become an interested stockholder.

After the five year prohibition, any business combination between the Maryland corporation and an interested stockholder generally must be recommended by the board of directors of the corporation and approved by the affirmative vote of at least:

The business combination statute may discourage others from trying to acquire control of us and increase the difficulty of consummating any offer, including potential acquisitions that might involve a premium price for our common stock or otherwise be in the best interest of our stockholders.

In addition, the MGCL provides that holders of "control shares" of a Maryland corporation acquired in a "control share acquisition" will not have voting rights with respect to the control shares except to the extent approved by a vote of two-thirds of the votes entitled to be cast on the matter, excluding shares of stock owned by the acquiror, by officers of the corporation or by directors who are employees of the corporation. "Control shares" means voting shares of stock that, if aggregated with all other shares of stock owned by the acquiror or in respect of which the acquiror is able to exercise or direct the exercise of voting power (except solely by virtue of a revocable proxy), would entitle the acquiror to exercise voting power in electing directors within one of the following ranges of voting power: (i) one-tenth or more but less than one-third; (ii) one-third or more but less than a majority; or (iii) a majority or more of all voting power. A "control share acquisition" means the acquisition of

Additionally, other provisions of the MGCL permit our board of directors, without stockholder approval and regardless of what is provided in our charter or bylaws, to implement certain other takeover defenses, some of which have been implemented through provisions in our charter or bylaws unrelated to the provisions of the MGCL and others have not been implemented by our board of directors.MGCL. Such takeover defenses, to the extent implemented now or in the future, may have the effect of inhibiting a third party from making us an acquisition proposal or of delaying, deferring or preventing a change in our control under circumstances that otherwise could provide our stockholders with an opportunity to realize a premium over the then-current market price.

Certain of our consolidated debt is not assumable and may be subject to significant prepayment penalties. These limitations could deter a change in control of our company.

We are subject to various federal, state and local environmental and health and safety laws that can impose liability on current and former property owners or operators for the clean-up of certain hazardous substances released on a property or of contamination at any facility (e.g., a landfill) to which we have sent hazardous substances for treatment or disposal, without regard to fault or whether the release or disposal was in compliance with law. Being held responsible for such a clean-up could result in significant cost to us and have a material adverse effect on our financial condition and results of operations.

Our properties may be subject to risks relating to current or future laws, including laws benefiting disabled persons, such as the Americans with Disabilities Act, or ADA, and state or local zoning, construction or other regulations. Compliance with such laws may require significant property modifications in the future, which could be costly and non-compliancecostly. Non-compliance could result in fines being levied against us in the future. Such costs could have an adverse impact on our cash flows and ability to pay dividends to stockholders.

Changing or new laws, regulations and standards relating to corporate governance and public disclosure, including SEC regulations and NYSE rules, can create uncertainty for public companies. These changed or new laws, regulations and standards are subject to varying interpretations in many cases due to their lack of specificity. As a result, their application in practice may evolve over time as new guidance is provided by regulatory and governing bodies, which could result in continuing uncertainty regarding compliance matters and higher costs necessitated by ongoing revisions to disclosure and governance practices. We are committed to maintaining high standards of corporate governance and public disclosure. If our efforts to comply with new or changed laws, regulations and standards differ from the activities intended by regulatory or governing bodies due to ambiguities related to practice, our reputation may be harmed.

Our efforts to comply with evolving laws, regulations and standards have resulted in, and are likely to continue to result in, increased general and administrative expenses and a diversion of management time and attention from revenue-generating activities to compliance activities. In particular, our continued efforts to comply with Section 404 of the Sarbanes-Oxley Act of 2002 and the related regulations regarding our required assessment of our internal controls over financial reporting and our external auditors' audit of that assessment have required the commitment of significant financial and managerial resources. We expect these efforts to require the continued commitment of significant resources. Further, our directors, chief executive officer and chief financial officer could face an increased risk of personal liability in connection with the performance of their duties. As a result, we may have difficulty attracting and retaining qualified directors and executive officers, which could harm our business.

We are required to pay real property taxes or payments in lieu of taxes in respect of our properties and such taxes may increase as our properties are reassessed by taxing authorities or as property tax rates change. An increase in the assessed value of our properties or our property tax rates could adversely impact our financial condition, results of operations and our ability to satisfy our debt service obligations and to pay dividends and distributions to our security holders.

Between January 1, 20202021 and December 31, 2020,2021, the closing sale price of our common stock on the New York Stock Exchange, or the NYSE, ranged from $37.90$59.91 to $98.56$87.78 per share. Our stock price may fluctuate in response to a number of events and factors, such as those described elsewhere in this "Risk Factors" section. Equity issuances or buybacks by us or the perception that such issuances or buybacks may occur may also affect the market price of our common stock.

Our charter authorizes our boardBoard of directorsDirectors to issue additional shares of common stock, preferred stock and convertible equity or debt without stockholder approval and without the requirement to offer rights of pre-emption to existing stockholders. Any such issuance could dilute our existing stockholders' interests. Also, any future series of preferred stock may have voting provisions that could delay or prevent a change of control of our company.

As with other publicly traded equity securities, the value of our common stock depends on various market conditions, which may change from time to time. In addition to the current economic environment and future volatility in the securities and credit markets, the following market conditions may affect the value of our common stock:

The market value of our common stock is based on a number of factors including, but not limited to, the market's perception of the current and future value of our assets, our growth potential and our current and potential future earnings and

U.S. federal income tax laws and the rules dealing with U.S. federal income taxation are continually under review by Congress, the IRS, and the U.S. Department of the Treasury. Any such changes could have an adverse effect on an investment in our shares or on the market value or the resale potential of our assets.

We are dependent on the efforts of Marc Holliday, our chairman and chief executive officer, and Andrew W. Mathias, our president. These officers have employment agreements which expire in January 20222025 and December 2021,2023, respectively. A loss of the services of either of these individuals could adversely affect our operations and could be negatively perceived by the market resulting in a decrease in our stock price.

Despite system redundancy, the implementation of security measures and the existence of a disaster recovery plan for our internal information technology systems, our systems are vulnerable to a number of risks including energy blackouts, natural disasters, terrorism, war, telecommunication failures and cyber attacks and intrusions, such as computer viruses, malware, attachments to e-mails, intrusion and unauthorized access, including from persons inside our organization or from persons outside our organization with access to our systems. The risk of a security breach or disruption, particularly through cyber attacks and intrusions, including by computer hackers, foreign governments and cyber terrorists, has generally increased as the number, intensity and sophistication of attempted attacks and instructions from around the world have increased. Our systems are critical to the operation of our business and any system failure, accident or security breach that causes interruptions in our operations could result in a material disruption to our business. We may also incur additional costs to remedy damages caused by such disruptions. Although we make efforts to maintain the security and integrity of our systems and have implemented various measures to manage the risk of a security breach or disruption, there can be no assurance that our security efforts and measures will be effective or that attempted security breaches or disruptions would not be successful or damaging. Any compromise of our security could also result in a violation of applicable privacy and other laws, significant legal and financial exposure, damage to our reputation, loss or misuse of the information (which may be confidential, proprietary and/or commercially sensitive in nature) and a loss of confidence in our security measures, which could harm our business.

See Item 7, "Management's Discussion and Analysis of Financial Condition and Results of Operations—Forward-looking Information," for additional disclosure regarding forward-looking statements.

As of December 31, 2020,2021, we did not have any unresolved comments with the staff of the SEC.