Exhibit 99.1

SELECTED COMBINING CONDENSED CONSOLIDATED PRO FORMA FINANCIAL DATA

On October 22, 2021, FSP 999 Peachtree Street LLC, (the “October Seller”), a wholly-owned subsidiary of Franklin Street Properties Corp. (“FSP Corp.” or the “Registrant”), sold a property (the “October Property”) to Piedmont 999 Peachtree One, LLC and Piedmont 999 Peachtree Two, LLC (as successors-by-assignment to Piedmont Operating Partnership, LP, and together the “October Buyer”). The purchase price for the October Property was $223,900,000. There were no material relationships, other than in respect of the Purchase and Sale Agreement dated October 13, 2021, as amended, relating to the sale of the October Property among the October Seller and the October Buyer, or any of their respective affiliates. The October Property is located at 999 Peachtree Street, Atlanta, Georgia.

On May 27, 2021, FSP One Ravinia Drive LLC, FSP Two Ravinia Drive LLC, and FSP One Overton Park LLC (together, the “May Seller”), each a wholly-owned subsidiary of FSP Corp., sold three properties (collectively, the “May Properties” and together with the October Property, the “Properties”) to One Ravinia Owner LLC, Two Ravinia Owner LLC, and One Overton Owner LLC (together, the “May Buyer”), each an affiliate of Crocker Partners LLC.  The aggregate purchase price for the May Properties was $219,500,000.  There were no material relationships, other than in respect of the Purchase and Sale Agreement dated March 5, 2021, as amended, related to the sale of the May Properties among the May Seller and the May Buyer, or any of their respective affiliates.  The May Properties are located at One Ravinia Drive NE, Dunwoody, Georgia, Two Ravinia Drive NE, Dunwoody, Georgia, and 3625 Cumberland Boulevard SE, Atlanta, Georgia.

The following unaudited pro forma condensed consolidated financial statements of FSP Corp. have been prepared to show the pro forma effect of the dispositions of the Properties and subsequent partial repayment of outstanding borrowings under the BAML Credit Facility and have been prepared in accordance with Article 11 of Regulation S-X by applying pro forma adjustments to our historical combined financial information. The pro forma transaction accounting adjustments for the sales consist of those necessary to account for the dispositions. The pro forma other transaction accounting adjustments consists of those necessary to account for the impact of debt repaid using the net proceeds from the sale and the effects on interest expense and deferred financing costs. The unaudited pro forma condensed consolidated financial statements are based upon the historical consolidated financial statements of FSP Corp. included in its Annual Report on Form 10-K for the year ended December 31, 2020, and its Quarterly Report on Form 10-Q for the quarter ended June 30, 2021. The pro forma consolidated balance sheet has been presented as if the disposition of the October Property and a partial repayment of the BAML Credit Facility had occurred as of June 30, 2021. The pro forma condensed consolidated statements of operations for the six months ended June 30, 2021 and for the year ended December 31, 2020 are presented as if the dispositions and partial repayment of the BAML Credit Facility were completed on January 1, 2020.

The unaudited pro forma condensed consolidated financial statements are not necessarily indicative of the actual results of operations of the Properties for the periods indicated, nor do they purport to represent the financial condition or results of operations of FSP Corp. for any future period. These unaudited pro forma financial statements are provided for informational purposes only. FSP Corp.’s financial position and results of operations after the dispositions of the Properties may be significantly different than what is presented in these unaudited pro forma financial statements. In the opinion of FSP Corp. management, all material adjustments necessary to reflect the effect of the above transactions have been made.

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Franklin Street Properties Corp.

Unaudited Condensed Consolidated Pro Forma Balance Sheets

June 30, 2021

(dollars in thousands, except per share amounts)

				Transaction			Other Transaction
		Historical		Accounting			Accounting
		FSP Corp. (a)		Adjustments			Adjustments			Pro Forma
Assets:
Real estate assets, net	$	1,413,547	$	(115,791)	(b)	$	-		$	1,297,756
Acquired real estate leases, net		21,932		(3,678)	(b)		-			18,254
Cash, cash equivalents and restricted cash		24,180		216,682	(c)		(200,000)	(d)		40,862
Tenant rents receivable, net		3,116		-			-			3,116
Straight-line rents receivable, net		61,475		(8,541)	(b)		-			52,934
Prepaid expenses and other assets		5,405		-			-			5,405
Related party mortgage loan receivable		21,000		-			-			21,000
Office computers & furniture, net		167		-			-			167
Deferred leasing commissions, net		49,793		(5,080)	(b)		-			44,713
Total assets	$	1,600,615	$	83,592		$	(200,000)		$	1,484,207
Liabilities and stockholders' equity:
Liabilities:
Term loan payable, net of unamortized financing costs	$	563,151	$	-		$	(199,374)	(d)	$	363,777
Series A & Series B Senior Notes		199,260		-			-			199,260
Accounts payable and accrued expenses		50,799		(1,592)	(b)		-			49,207
Accrued compensation		2,309		-			-			2,309
Tenant security deposits		6,807		(1,126)	(b)		-			5,681
Lease liability		1,350		-			-			1,350
Other liabilities: derivative liabilities		9,425		-			-			9,425
Acquired unfavorable real estate leases, net		829		(95)	(b)		-			734
Total liabilities		833,930		(2,813)			(199,374)			631,743
Stockholders' Equity:
Preferred stock		-		-			-			-
Common stock		11		-			-			11
Additional paid in capital		1,357,469		-			-			1,357,469
Accumulated other comprehensive loss		(9,425)		-			-			(9,425)
Accumulated distributions in excess of accumulated earnings		(581,370)		86,405	(e)		(626)	(d)		(495,591)
Total stockholders' equity		766,685		86,405			(626)			852,464
Total liabilities and stockholders' equity	$	1,600,615	$	83,592		$	(200,000)		$	1,484,207

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Franklin Street Properties Corp.

Unaudited Pro Forma Condensed Consolidated Statements of Operations

For the Six Months Ended

June 30, 2021

(dollars in thousands, except per share amounts)

									Transaction			Other Transaction
		Historical		May Properties			Historical FSP Corp.		Accounting			Accounting
		FSP Corp. (f)		Actuals			Less May Properties (i)		Adjustments			Adjustments			Pro Forma
Revenues:
Rental	$	114,345	$	(9,465)	(g)	$	104,880	$	(9,690)	(j)	$	-		$	95,190
Related party revenue:
Management fees and interest from loans		827		-			827		-			-			827
Other		12		-			12		-			-			12
Total revenues		115,184		(9,465)			105,719		(9,690)			-			96,029
Expenses:
Real estate operating expenses		31,291		(3,363)	(g)		27,928		(2,265)	(j)		-			25,663
Real estate taxes and insurance		24,261		(1,548)	(g)		22,713		(1,642)	(j)		-			21,071
Depreciation and amortization		43,517		(2,713)	(g)		40,804		(3,252)	(j)		-			37,552
General and administrative		8,108		(11)	(g)		8,097		(10)	(j)		-			8,087
Interest		18,654		-			18,654		-			(1,474)	(m)		17,180
Total expenses		125,831		(7,635)			118,196		(7,169)			(1,474)			109,553
Loss on extinguishment of debt		(167)		-			(167)		-			-			(167)
Gain (loss) on sale of properties		20,626		(22,774)	(h)		(2,148)		-			-			(2,148)
Income (loss) before taxes on income		9,812		(24,604)			(14,792)		(2,521)			1,474			(15,839)
Tax expense on income		123		-			123		-			-			123
Net income (loss)	$	9,689	$	(24,604)		$	(14,915)	$	(2,521)		$	1,474		$	(15,962)
Weighted average number of shares outstanding,
basic and diluted		107,344					107,344								107,344
Net loss per share, basic and diluted	$	0.09				$	(0.14)							$	(0.15)

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Franklin Street Properties Corp.

Unaudited Pro Forma Condensed Consolidated Statements of Operations

For the Year Ended

December 31, 2020

(dollars in thousands, except per share amounts)

									Transaction			Other Transaction
		Historical		May Properties			Historical FSP Corp.		Accounting			Accounting
		FSP Corp. (f)		Actuals			Less May Properties (i)		Adjustments			Adjustments			Pro Forma
Revenues:
Rental	$	244,207	$	(25,283)	(g)	$	218,924	$	(19,545)	(j)	$	-		$	199,379
Related party revenue:
Management fees and interest from loans		1,610		-			1,610		-			-			1,610
Other		31		-			31		-			-			31
Total revenues		245,848		(25,283)			220,565		(19,545)			-			201,020
Expenses:
Real estate operating expenses		66,940		(8,776)	(g)		58,164		(4,921)	(j)		-			53,243
Real estate taxes and insurance		48,390		(3,797)	(g)		44,593		(3,127)	(j)		-			41,466
Depreciation and amortization		88,558		(9,803)	(g)		78,755		(7,356)	(j)		-			71,399
General and administrative		14,997		(60)	(g)		14,937		(26)	(j)		-			14,911
Interest		36,026		-			36,026		-			(3,995)	(m)		32,031
Total expenses		254,911		(22,436)			232,475		(15,430)			(3,995)			213,050
Loss on extinguishment of debt		-		-			-		-			(1,236)	(l)		(1,236)
Gain on sale of property		41,928		22,774	(h)		64,702		86,405	(k)		-			151,107
Income before taxes on income		32,865		19,927			52,792		82,290			2,759			137,841
Tax expense on income		250		-			250		-			-			250
Net income	$	32,615	$	19,927		$	52,542	$	82,290		$	2,759		$	137,591
Weighted average number of shares outstanding,
basic and diluted		107,303					107,303								107,303
Net income per share, basic and diluted	$	0.30				$	0.49							$	1.28

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FRANKLIN STREET PROPERTIES CORP.

NOTES TO UNAUDITED CONDENSED CONSOLIDATED

PRO FORMA FINANCIAL STATEMENTS

(dollars in thousands, except per share amounts)

The above unaudited condensed consolidated pro forma financial statement presentation has been prepared based upon certain pro forma adjustments to the historical consolidated financial statements of FSP Corp.  Certain assumptions regarding the operations of FSP Corp. have been made in connection with the preparation of the condensed consolidated financial pro forma information.  These assumptions are as follows:

1. Adjustments to Pro Forma Condensed Consolidated Balance Sheet

(a) Represents FSP Corp.’s historical condensed consolidated balance sheet as of June 30, 2021, which was derived from FSP Corp.’s quarterly report on Form 10-Q for the quarterly period ended June 30, 2021 and reflect the gain on disposal of the May Properties. FSP Corp. elected to be, and is qualified as, a real estate investment trust for federal income tax purposes.  FSP Corp. has met the various required tests; therefore, no provision for federal or state income taxes has been reflected on real estate operations.

FSP Corp. has subsidiaries which are not in the business of real estate operations.  Those subsidiaries are taxable as real estate investment trust subsidiaries, or TRS, and are subject to income taxes at statutory tax rates.  The taxes on income shown in the pro forma condensed consolidated statements of operations are the taxes on the income of the TRS.  There are no material items that would cause a deferred tax asset or a deferred tax liability.

(b) Represents FSP Corp.’s disposition of the October Property and the necessary adjustments to eliminate the real estate assets, rights and obligations associated with tenant leasing arrangements, accrued property taxes and related intangible assets based on their carrying values as of June 30, 2021 associated with the disposition of the property.

(c) Represents the net disposition proceeds received. The gross sales price of the October Property was $223,900 before purchase credits of $2,434, estimated disposition related costs of $2,066, payment of $1,592 of property taxes and payment of security deposits to the Buyer of $1,126.

(d) Represents a partial repayment of the BAML Credit Facility in the amount of $200,000 from the net disposition proceeds received from the disposition of the October Property, as described above in (c). The partial repayment resulted in a loss on extinguishment of debt of $626. The net reduction of debt associated with the BAML Credit Facility was $199,374.

(e) Represents FSP Corp.’s disposition of the October Property and the related nonrecurring estimated gain on sale. The gain has been calculated based upon the net disposition proceeds of $216,682, as described above in (c), less the carrying amounts as of June 30, 2021 of assets and liabilities disposed of on October 22, 2021.

2. Adjustments to Pro Forma Condensed Consolidated Statements of Operation

(f) Represents FSP Corp.’s historical condensed consolidated statements of operations for the six months ended June 30, 2021 and the year ended December 31, 2020, which were derived from FSP Corp.’s quarterly report on Form 10-Q for the six months ended June 30, 2021 and the annual report on Form 10-K for the year ended December 31, 2020, respectively. The condensed consolidated statement of

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operations for the year ended December 31, 2020 includes a nonrecurring gain of $41,928 for the sale of a property unrelated to the properties sold on May 27, 2021 and October 22, 2021. The condensed consolidated statement of operations for the six months ended June 30, 2021 includes a nonrecurring loss of $2,148 for the sale of a property unrelated to the properties sold on May 27, 2021 and October 22, 2021.

(g) Represents FSP Corp.’s disposition of the May Properties and the necessary adjustment to eliminate the impact of historical rental income, real estate operating expenses, real estate taxes and insurance, depreciation and amortization and general and administrative expenses associated with the May Properties.

(h) Represents the disposition of the May Properties and the related nonrecurring estimated gain on sale. The gain has been calculated based upon the net disposition proceeds of $211,856, less the carrying amounts as of May 27, 2021 of assets and liabilities disposed of on May 27, 2021.

(i) Represents FSP Corp.’s historical condensed consolidated statements of operations for the six months ended June 30, 2021 and year ended December 31, 2020, less the effect of the sale of the May Properties.

(j) Represents FSP Corp.’s disposition of the October Property and the necessary adjustment to eliminate the impact of historical rental income, real estate operating expenses, real estate taxes and insurance, depreciation and amortization and general and administrative expenses associated with the October Property.

(k) Represents the disposition of the October Property and the related nonrecurring estimated gain on sale. The gain has been calculated based upon the net disposition proceeds of $216,682 as described above in (c), less the carrying amounts as of June 30, 2021 of assets and liabilities disposed of on October 22, 2021.

(l) Represents a loss on extinguishment if the partial repayment on the BAML Credit Facility occurred on January 1, 2020.

(m) Represents the amount of interest saved for the six months ended June 30, 2021 and for the year ended December 31, 2020 if the partial repayment on the BAML Credit Facility occurred on January 1, 2020.

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