Exhibit 99.1

Filed pursuant to Rule 425 under the Securities Act of 1933

and deemed filed pursuant to Rule 14a-12 of the Securities Exchange Act of 1934

Filing Person: Corporate Property Associates 15 Incorporated

Subject Company: Corporate Property Associates 15 Incorporated

Commission File Number: 000-50249

Corporate Property Associates 15 Incorporated

Supplemental Unaudited Information

As of March 31, 2012

As used in this supplemental package, the terms “the Company,” “we,” “us” and “our” include Corporate Property Associates 15 Incorporated (“CPA^®:15”), its consolidated subsidiaries and predecessors, unless otherwise indicated.

Important Note Regarding Non-GAAP Financial Measures

This supplemental package includes non-GAAP measures, including funds from operations (“FFO”), modified funds from operations (“MFFO”), and adjusted cash flow from operating activities (“ACFO”). A description of these non-GAAP measures and reconciliations to the most directly comparable GAAP measures are provided in this supplemental package.

Forward-Looking Statements

This supplemental package contains forward-looking statements within the meaning of the Federal securities laws. It is important to note that our actual results could be materially different from those projected in such forward-looking statements. You should exercise caution in relying on forward-looking statements as they involve known and unknown risks, uncertainties and other factors that may materially affect our future results, performance, achievements or transactions. Information on factors which could impact actual results and forward-looking statements contained herein is included in our filings with the Securities and Exchange Commission, including but not limited to our Annual Report on Form 10-K for the year ended December 31, 2011. We do not undertake to revise or update any forward-looking statements.

Corporate Property Associates 15 Incorporated

Reconciliation of Net Income Attributable to CPA^®:15 Shareholders

to Modified Funds From Operations (MFFO) (Unaudited)

(in thousands, except share and per share amounts)

CPA^® :15 3/31/2012 Supplemental 8-K — 2

MFFO per share calculation:

Non-GAAP Financial Disclosure

Funds from Operations (“FFO”) and Modified Funds from Operations (“MFFO”)

Due to certain unique operating characteristics of real estate companies, as discussed below, NAREIT has promulgated a measure known as funds from operations, or FFO, which we believe to be an appropriate supplemental measure to reflect the operating performance of a real estate investment trust, or REIT. The use of FFO is recommended by the REIT industry as a supplemental performance measure. FFO is not equivalent to nor a substitute for net income or loss as determined under GAAP.

We define FFO, a non-GAAP measure, consistent with the standards established by the White Paper on FFO approved by the Board of Governors of NAREIT, as revised in February 2004, or the White Paper. The White Paper defines FFO as net income or loss computed in accordance with GAAP, excluding gains or losses from sales of property, impairment charges on real estate and depreciation and amortization; and after adjustments for unconsolidated partnerships and jointly-owned investments. Adjustments for unconsolidated partnerships and jointly-owned investments are calculated to reflect FFO. Our FFO calculation complies with NAREIT’s policy described above.

CPA^® :15 3/31/2012 Supplemental 8-K — 3

The historical accounting convention used for real estate assets requires straight-line depreciation of buildings and improvements, which implies that the value of real estate assets diminishes predictably over time, especially if such assets are not adequately maintained or repaired and renovated as required by relevant circumstances and/or is requested or required by lessees for operational purposes in order to maintain the value disclosed. We believe that, since real estate values historically rise and fall with market conditions, including inflation, interest rates, the business cycle, unemployment and consumer spending, presentations of operating results for a REIT using historical accounting for depreciation may be less informative. Historical accounting for real estate involves the use of GAAP. Any other method of accounting for real estate such as the fair value method cannot be construed to be any more accurate or relevant than the comparable methodologies of real estate valuation found in GAAP. Nevertheless, we believe that the use of FFO, which excludes the impact of real estate-related depreciation and amortization as well as impairment charges of real estate-related assets, provides a more complete understanding of our performance to investors and to management, and when compared year over year, reflects the impact on our operations from trends in occupancy rates, rental rates, operating costs, general and administrative expenses, and interest costs, which may not be immediately apparent from net income. In particular, we believe it is appropriate to disregard impairment charges, as this is a fair value adjustment that is largely based on market fluctuations and assessments regarding general market conditions which can change over time. An asset will only be evaluated for impairment if certain impairment indications exist and if the carrying, or book value, exceeds the total estimated undiscounted future cash flows (including net rental and lease revenues, net proceeds on the sale of the property, and any other ancillary cash flows at a property or group level under GAAP) from such asset. Investors should note, however, that determinations of whether impairment charges have been incurred are based partly on anticipated operating performance, because estimated undiscounted future cash flows from a property, including estimated future net rental and lease revenues, net proceeds on the sale of the property, and certain other ancillary cash flows, are taken into account in determining whether an impairment charge has been incurred. While impairment charges are excluded from the calculation of FFO described above, investors are cautioned that, due to the fact that impairments are based on estimated future undiscounted cash flows and the relatively limited term of our operations, it could be difficult to recover any impairment charges. However, FFO and MFFO, as described below, should not be construed to be more relevant or accurate than the current GAAP methodology in calculating net income or in its applicability in evaluating the operating performance of the company. The method utilized to evaluate the value and performance of real estate under GAAP should be construed as a more relevant measure of operational performance and considered more prominently than the non-GAAP FFO and MFFO measures and the adjustments to GAAP in calculating FFO and MFFO.

Changes in the accounting and reporting promulgations under GAAP (for acquisition fees and expenses from a capitalization/depreciation model to an expensed-as-incurred model) were put into effect in 2009. These other changes to GAAP accounting for real estate subsequent to the establishment of NAREIT’s definition of FFO have prompted an increase in cash-settled expenses, specifically acquisition fees and expenses for all industries as items that are expensed under GAAP, that are typically accounted for as operating expenses. Management believes these fees and expenses do not affect our overall long-term operating performance. Publicly registered, non-listed REITs typically have a significant amount of acquisition activity and are substantially more dynamic during their initial years of investment and operation. While other start-up entities may also experience significant acquisition activity during their initial years, we believe that non-listed REITs are unique in that they have a limited life with targeted exit strategies within a relatively limited time frame after acquisition activity ceases. In the prospectus for our follow-on offering dated March 19, 2003 (the “Prospectus”), we stated our intention to begin considering liquidity events (i.e., listing of our common stock on a national exchange, a merger or sale of our assets or another similar transaction) for investors generally commencing eight years following the investment of substantially all of the proceeds from our public offerings, which occurred in 2004, and on February 17, 2012 we entered into an agreement to merge with and into a subsidiary of WPC. Thus, we do not intend to continuously purchase assets and intend to have a limited life. Due to the above factors and other unique features of publicly registered, non-listed REITs, the Investment Program Association (“IPA”), an industry trade group, has standardized a measure known as MFFO, which the IPA has recommended as a supplemental measure for publicly registered non-listed REITs and which we believe to be another appropriate supplemental measure to reflect the operating performance of a non-listed REIT having the characteristics described above. MFFO is not equivalent to our net income or loss as determined under GAAP, and MFFO may not be a useful measure of the impact of long-term operating performance on value if we do not continue to operate with a limited life and targeted exit strategy, as currently intended. We believe that, because MFFO excludes costs that we consider more reflective of investing activities and other non-operating items included in FFO and also excludes acquisition fees and expenses that affect our operations only in periods in which properties are acquired, MFFO can provide, on a going forward basis, an indication of the sustainability (that is, the capacity to continue to be maintained) of our operating performance after the period in which we are acquiring properties and once our portfolio is in place. By providing MFFO, we believe we are presenting useful information that assists investors and analysts to better assess the sustainability of our operating performance now that our offering has been completed and essentially all of our properties have been acquired. We also believe that MFFO is a recognized measure of sustainable operating performance by the non-listed REIT industry. Further, we believe MFFO is useful in comparing the sustainability of our operating performance since our offering and essentially all of our acquisitions are completed with the sustainability of the operating performance of other real estate companies that are not as involved in acquisition activities. Investors are cautioned that MFFO should only be used to assess the sustainability of a company’s operating performance after a company’s offering has been completed and properties have been acquired, as it excludes acquisition costs that have a negative effect on a company’s operating performance during the periods in which properties are acquired.

CPA^® :15 3/31/2012 Supplemental 8-K — 4

We define MFFO, a non-GAAP measure, consistent with the IPA’s Guideline 2010-01, Supplemental Performance Measure for Publicly Registered, Non-Listed REITs: Modified Funds from Operations, or the Practice Guideline, issued by the IPA in November 2010. The Practice Guideline defines MFFO as FFO further adjusted for the following items, as applicable, included in the determination of GAAP net income: acquisition fees and expenses; amounts relating to deferred rent receivables and amortization of above and below market leases and liabilities (which are adjusted in order to reflect such payments from a GAAP accrual basis to a cash basis of disclosing the rent and lease payments); accretion of discounts and amortization of premiums on debt investments; nonrecurring impairments of real estate-related investments (i.e., infrequent or unusual, not reasonably likely to recur in the ordinary course of business); mark-to-market adjustments included in net income; nonrecurring gains or losses included in net income from the extinguishment or sale of debt, hedges, foreign exchange, derivatives or securities holdings where trading of such holdings is not a fundamental attribute of the business plan, unrealized gains or losses resulting from consolidation from, or deconsolidation to, equity accounting, and after adjustments for consolidated and unconsolidated partnerships and jointly-owned investments, with such adjustments calculated to reflect MFFO on the same basis. The accretion of discounts and amortization of premiums on debt investments, nonrecurring unrealized gains and losses on hedges, foreign exchange, derivatives or securities holdings, unrealized gains and losses resulting from consolidations, as well as other listed cash flow adjustments are adjustments made to net income in calculating the cash flows provided by operating activities and, in some cases, reflect gains or losses which are unrealized and may not ultimately be realized. While we are responsible for managing interest rate, hedge and foreign exchange risk, we retain an outside consultant to review all our hedging agreements. Inasmuch as interest rate hedges are not a fundamental part of our operations, we believe it is appropriate to exclude such infrequent gains and losses in calculating MFFO, as such gains and losses are not reflective of on-going operations.

Our MFFO calculation complies with the IPA’s Practice Guideline described above. In calculating MFFO, we exclude acquisition-related expenses, amortization of above- and below-market leases, fair value adjustments of derivative financial instruments, deferred rent receivables and the adjustments of such items related to noncontrolling interests. Under GAAP, acquisition fees and expenses are characterized as operating expenses in determining operating net income. These expenses are paid in cash by a company. All paid and accrued acquisition fees and expenses will have negative effects on returns to investors, the potential for future distributions, and cash flows generated by the company, unless earnings from operations or net sales proceeds from the disposition of other properties are generated to cover the purchase price of the property, these fees and expenses and other costs related to such property. Further, under GAAP, certain contemplated non-cash fair value and other non-cash adjustments are considered operating non-cash adjustments to net income in determining cash flow from operating activities. In addition, we view fair value adjustments of derivatives and gains and losses from dispositions of assets as infrequent items or items which are unrealized and may not ultimately be realized, and which are not reflective of on-going operations and are therefore typically adjusted for assessing operating performance.

Our management uses MFFO and the adjustments used to calculate it in order to evaluate our performance against other non-listed REITs which have limited lives with short and defined acquisition periods and targeted exit strategies shortly thereafter. As noted above, MFFO may not be a useful measure of the impact of long-term operating performance on value if we do not continue to operate in this manner. We believe that our use of MFFO and the adjustments used to calculate it allow us to present our performance in a manner that reflects certain characteristics that are unique to non-listed REITs, such as their limited life, limited and defined acquisition period and targeted exit strategy, and hence that the use of such measures is useful to investors. For example, acquisition costs were generally funded from the proceeds of our offering and other financing sources and not from operations. By excluding expensed acquisition costs, the use of MFFO provides information consistent with management’s analysis of the operating performance of the properties. Additionally, fair value adjustments, which are based on the impact of current market fluctuations and underlying assessments of general market conditions, but can also result from operational factors such as rental and occupancy rates, may not be directly related or attributable to our current operating performance. By excluding such changes that may reflect anticipated and unrealized gains or losses, we believe MFFO provides useful supplemental information.

Presentation of this information is intended to provide useful information to investors as they compare the operating performance of different REITs, although it should be noted that not all REITs calculate FFO and MFFO the same way, so comparisons with other REITs may not be meaningful. Furthermore, FFO and MFFO are not necessarily indicative of cash flow available to fund cash needs and should not be considered as an alternative to net income (loss) or income (loss) from continuing operations as an indication of our performance, as an alternative to cash flows from operations as an indication of our liquidity, or indicative of funds available to fund our cash needs including our ability to make distributions to our stockholders. FFO and MFFO should be reviewed in conjunction with other GAAP measurements as an indication of our performance.

Neither the SEC, NAREIT nor any other regulatory body has passed judgment on the acceptability of the adjustments that we use to calculate FFO or MFFO. In the future, the SEC, NAREIT or another regulatory body may decide to standardize the allowable adjustments across the non-listed REIT industry and we would have to adjust our calculation and characterization of FFO or MFFO accordingly.

CPA^® :15 3/31/2012 Supplemental 8-K — 5

Corporate Property Associates 15 Incorporated

Adjusted Cash Flow from Operating Activities (ACFO) (Unaudited)

(in thousands, except share and per share amounts)

Non-GAAP Financial Disclosure

Adjusted Cash Flow from Operating Activities (“ACFO”)

ACFO refers to our cash flow from operating activities (as computed in accordance with GAAP) adjusted, where applicable, primarily to: add cash distributions that we receive from our investments in unconsolidated jointly-owned real estate investment entities in excess of our equity income; subtract cash distributions that we make to our noncontrolling partners in jointly-owned real estate investment entities that we consolidate; and eliminate changes in working capital. We hold a number of interests in jointly-owned real estate investment entities, and we believe that adjusting our GAAP cash flow provided by operating activities to reflect these actual cash receipts and cash payments, as well as eliminating the effect of timing differences between the payment of certain liabilities and the receipt of certain receivables in a period other than that in which the item is recognized, may give investors additional information about our actual cash flow that is not incorporated in cash flow from operating activities as defined by GAAP.

We believe that ACFO is a useful supplemental measure for assessing the cash flow generated from our core operations as it gives investors important information about our liquidity that is not provided within cash flow from operating activities as defined by GAAP, and we use this measure when evaluating distributions to shareholders. While we believe that ACFO is an important supplemental measure, it should not be considered as an alternative to cash flow from operating activities as a measure of liquidity. This non-GAAP measure should be used in conjunction with cash flow from operating activities as defined by GAAP.

CPA^® :15 3/31/2012 Supplemental 8-K — 6

Corporate Property Associates 15 Incorporated

Portfolio Diversification as of March 31, 2012 (Unaudited)

Top Ten Tenants by Rent (Pro Rata Basis)

(in thousands, except percentages)

Portfolio

At March 31, 2012, our portfolio was comprised of our full or partial ownership interests in 313 properties, substantially all of which were triple-net leased to 76 tenants, and totaled approximately 28 million square feet (on a pro rata basis), with an occupancy rate of approximately 99%.

CPA^® :15 3/31/2012 Supplemental 8-K — 7

Corporate Property Associates 15 Incorporated

Portfolio Diversification as of March 31, 2012 (Unaudited)

by Geography and Property Type (Pro Rata Basis)

(in thousands, except percentages)

CPA^® :15 3/31/2012 Supplemental 8-K — 8

Corporate Property Associates 15 Incorporated

Portfolio Diversification as of March 31, 2012 (Unaudited)

by Tenant Industry (Pro Rata Basis)

(in thousands, except percentages)

CPA^® :15 3/31/2012 Supplemental 8-K — 9