6. Commitments and Contingencies

General

In the normal course of business, the Company guarantees its performance of services or indemnifies third parties against its negligence.

The Company has letter of credit and performance obligations of approximately $12.5 million related to lender and development requirements.

Certain of the Company's joint venture agreements include provisions whereby, at certain specified times, each partner has the right to initiate a purchase or sale of its interest in the joint ventures. Under these provisions, the Company is not compelled to purchase the interest of its outside joint venture partners.

In connection with the Company's assumption of the General Motors Building's secured loan by the Company's unconsolidated joint venture, 767 Venture, LLC, the Company guaranteed the unconsolidated joint venture's obligation to fund various escrows, including tenant improvements, taxes and insurance in lieu of cash deposits. As of March 31, 2010, the maximum funding obligation under the guarantee was approximately $16.3 million. In connection with the Company's refinancing of the 125 West 55^th Street property's secured loan by the Company's unconsolidated joint venture, 125 West 55^th Street Venture LLC, the Company has guaranteed the unconsolidated joint venture's obligation to fund an escrow related to certain lease rollover costs in lieu of an initial cash deposit for the full amount. The maximum funding obligation under the guarantee was $21.3 million. At closing, the joint venture funded a $10.0 million cash deposit into the escrow account and the remaining $11.3 million will be further reduced with scheduled monthly deposits into the escrow account from operating cash flows. As of March 31, 2010, the maximum funding obligation under the guarantee was $11.3 million. From time to time, the Company (or the applicable joint venture) has also agreed to guarantee portions of the principal, interest or other amounts in connection with other unconsolidated joint venture borrowings. In addition to the financial guarantees referenced above, the Company has agreed to customary environmental indemnifications and nonrecourse carve-outs (e.g., guarantees against fraud, mis representation and bankruptcy) on certain of its unconsolidated joint venture loans.

Insurance

The Company carries insurance coverage on its properties of types and in amounts and with deductibles that it believes are in line with coverage customarily obtained by owners of similar properties. In response to the uncertainty in the insurance market following the terrorist attacks of September 11, 2001, the Federal Terrorism Risk Insurance Act (as amended, "TRIA") was enacted in November 2002 to require regulated insurers to make available coverage for "certified" acts of terrorism (as defined by the statute). The expiration date of TRIA was extended to December 31, 2014 by the Terrorism Risk Insurance Program Reauthorization Act of 2007 ("TRIPRA"). Currently, the Company's property insurance program per occurrence limits are $1.0 billion for its portfolio insurance program, including coverage for acts of terrorism certified under TRIA. The Company currently insures certain properties, including the General Motors Building located at 767 Fifth Avenue in New York, New York ("767 Fi fth Avenue"), in separate stand alone insurance programs. The property insurance program per occurrence limits for 767 Fifth Avenue are $1.625 billion, including coverage for acts of terrorism certified under TRIA, with $1.375 billion of coverage for losses in excess of $250 million being provided by NYXP, LLC, as a direct insurer. The Company also currently carries nuclear, biological, chemical and radiological terrorism insurance coverage ("NBCR Coverage") for acts of terrorism certified under TRIA, which is provided by IXP, LLC as a direct insurer, for the properties in our portfolio, including 767 Fifth Avenue, but excluding the properties owned by the Company's Value-Added Fund and certain other properties owned in joint ventures with third parties or which we manage. The per occurrence limit for NBCR Coverage is $1.0 billion. Under TRIA, after the payment of the required deductible and coinsurance, the NBCR Coverage is backstopped by the Federal Government if the aggregate industry insured losses resul ting from a certified act of terrorism exceed a "program trigger." The program trigger is $100 million and the coinsurance is 15%. Under TRIPRA, if the Federal Government pays out for a loss under TRIA, it is mandatory that the Federal Government recoup the full amount of the loss from insurers offering TRIA coverage after the payment of the loss pursuant to a formula in TRIPRA. The Company may elect to terminate the NBCR Coverage if the Federal Government seeks recoupment for losses paid under TRIA, if there is a change in its portfolio or for any other reason. The Company intends to continue to monitor the scope, nature and cost of available terrorism insurance and maintain insurance in amounts and on terms that are commercially reasonable.

The Company also currently carries earthquake insurance on its properties located in areas known to be subject to earthquakes in an amount and subject to self-insurance that the Company believes are commercially reasonable. In addition, this insurance is subject to a deductible in the amount of 5% of the value of the affected property. Specifically, the Company currently carries earthquake insurance which covers its San Francisco region with a $120 million per occurrence limit and a $120 million annual aggregate limit, $20 million of which is provided by IXP, LLC, as a direct insurer. The amount of the Company's earthquake insurance coverage may not be sufficient to cover losses from earthquakes. In addition, the amount of earthquake coverage could impact the Company's ability to finance properties subject to earthquake risk. The Company may discontinue earthquake insurance on some or all of its properties in the future if the premiums exceed the Company's estimation of the value of t he coverage.

IXP, LLC ("IXP"), a captive insurance company which is a wholly-owned subsidiary of the Company, acts as a direct insurer with respect to a portion of the Company's earthquake insurance coverage for its Greater San Francisco properties and the Company's NBCR Coverage for acts of terrorism certified under TRIA. NYXP, LLC ("NYXP"), a captive insurance company which is a wholly-owned subsidiary of the Company, acts as a direct insurer with respect to a portion of the Company's coverage for acts of terrorism certified under TRIA for 767 Fifth Avenue. Currently, NYXP only insures losses which exceed the program trigger under TRIA and NYXP reinsures with a third-party insurance company any coinsurance payable under TRIA. Insofar as the Company owns IXP and NYXP, it is responsible for their liquidity and capital resources, and the accounts of IXP and NYXP are part of the Company's consolidated financial statements. In particular, if a loss occurs which is covered by the Company's NBCR Covera ge but is less than the applicable program trigger under TRIA, IXP would be responsible for the full amount of the loss without any backstop by the Federal Government. IXP and NYXP would also be responsible for any recoupment charges by the Federal Government in the event losses are paid out and their insurance policies are maintained after the payout by the Federal Government. If the Company experiences a loss and IXP or NYXP are required to pay under their insurance policies, the Company would ultimately record the loss to the extent of the required payment. Therefore, insurance coverage provided by IXP and NYXP should not be considered as the equivalent of third-party insurance, but rather as a modified form of self-insurance.

The mortgages on the Company's properties typically contain requirements concerning the financial ratings of the insurers who provide policies covering the property. The Company provides the lenders on a regular basis with the identity of the insurance companies in the Company's insurance programs. The ratings of some of the Company's insurers are below the rating requirements in some of the Company's loan agreements and the lenders for these loans could attempt to claim an event of default has occurred under the loan. The Company believes it could obtain insurance with insurers which satisfy the rating requirements. Additionally, in the future, the Company's ability to obtain debt financing secured by individual properties, or the terms of such financing, may be adversely affected if lenders generally insist on ratings for insurers which are difficult to obtain or which result in a commercially unreasonable premium. There can be no assurance that a deficiency in the financial ratings of one or more of the Company's insurers will not have a material adverse effect on the Company.

The Company continues to monitor the state of the insurance market in general, and the scope and costs of coverage for acts of terrorism and California earthquake risk in particular, but the Company cannot anticipate what coverage will be available on commercially reasonable terms in future policy years. There are other types of losses, such as from wars or the presence of mold at the Company's properties, for which the Company cannot obtain insurance at all or at a reasonable cost. With respect to such losses and losses from acts of terrorism, earthquakes or other catastrophic events, if the Company experiences a loss that is uninsured or that exceeds policy limits, the Company could lose the capital invested in the damaged properties, as well as the anticipated future revenues from those properties. Depending on the specific circumstances of each affected property, it is possible that the Company could be liable for mortgage indebtedness or other obligations related to the property. Any such loss could materially and adversely affect the Company's business and financial condition and results of operations.

10. Stock Option and Incentive Plan

During the three months ended March 31, 2010, Boston Properties, Inc. issued 66,461 shares of restricted common stock and the Company issued 249,342 LTIP Units to employees and directors under the 1997 Stock Option and Incentive Plan (the "1997 Plan"). Employees and directors paid $0.01 per share of restricted common stock and $0.25 per LTIP Unit. The shares of restricted stock were valued at approximately $4.3 million ($64.87 per share). The LTIP Units were valued at approximately $15.1 million ($60.37 per unit fair value weighted-average) using a Monte Carlo simulation method model. The per unit fair value of each LTIP Unit granted was estimated on the date of grant using the following assumptions: an expected life of 5.7 years, a risk-free interest rate of 2.60% and an expected price volatility of 36.0%. An LTIP Unit is generally the economic equivalent of a share of restricted stock in Boston Properties, Inc. The aggregate value of the LTIP Units is included in noncontrolling inte rests in the Consolidated Balance Sheets. The restricted stock and LTIP Units granted to employees between January 1, 2004 and November 2006 vest over a five-year term. Grants of restricted stock and LTIP Units made in and after November 2006 vest in four equal annual installments. Restricted stock and LTIP Units are measured at fair value on the date of grant based on the number of shares or units granted, as adjusted for forfeitures, and the closing price of Boston Properties, Inc.'s Common Stock on the date of grant as quoted on the New York Stock Exchange. Such value is recognized as an expense ratably over the corresponding employee service period. Dividends paid on both vested and unvested shares of restricted stock are charged directly to Partners' Capital in the Consolidated Balance Sheets. Stock-based compensation expense associated with restricted stock, LTIP Units and 2008 OPP Units was approximately $13.8 million and $6.8 million for the three months ended March 31, 2010 and 2009, respectively. F or the three months ended March 31, 2010, stock-based compensation expense includes an aggregate of approximately $5.8 million of remaining previously unvested stock-based compensation granted between 2006 and 2009 to Edward H. Linde, Boston Properties, Inc.'s former Chief Executive Officer, which expense was accelerated as a result of his passing on January 10, 2010. At March 31, 2010, there was $42.6 million of unrecognized compensation expense related to unvested restricted stock and LTIP Units and $7.1 million of unrecognized compensation expense related to unvested 2008 OPP Units that is expected to be recognized over a weighted-average period of approximately 2.8 years. If upon the conclusion of the three-year measurement period in February 2011, the 2008 OPP Awards are not earned, and therefore the program is terminated, the Company will accelerate the then remaining unrecognized compensation expense totaling approximately $4.3 million during the first quarter of 2011.