Exhibit 99.4

MICROSEMI CORPORATION

UNAUDITED PRO FORMA CONDENSED COMBINED FINANCIAL STATEMENTS

As previously disclosed, on October 2, 2010, Microsemi entered into an Agreement and Plan of Merger by and among Artful Acquisition Corp., a California corporation and a wholly owned subsidiary of Microsemi (“Purchaser”), and Actel Corporation, a California corporation (“Actel”), pursuant to which, and on the terms and subject to the conditions thereof, Purchaser commenced a cash tender offer (the “Offer”) on October 4, 2010 to purchase all of the outstanding shares of Actel’s common stock, par value $0.001 per share, together with the associated preferred stock purchase rights issued in connection with and subject to the Preferred Stock Rights Agreement dated as of October 17, 2003, between Actel and Wells Fargo Bank, N.A., as amended (such rights together with the shares of common stock, the “Shares”), or such reduced amount of Shares as described therein, at a purchase price of $20.88 per Share, net to the tendering shareholder in cash, without interest and less any required withholding taxes (the “Per Share Amount”). On November 2, 2010, pursuant to the terms and conditions of the Merger Agreement, Purchaser was merged with and into Actel with Actel continuing as the surviving corporation and as a wholly owned subsidiary of Microsemi. At the effective time of the Merger, each Share outstanding (other than Shares owned by Actel, Microsemi, Purchaser, or any direct or indirect wholly owned subsidiary of Microsemi or Actel, or held by shareholders who properly demand and perfect dissenters’ rights under California law) was converted into the right to receive the Per Share Amount.

The unaudited pro forma condensed combined balance sheet combines Microsemi’s October 3, 2010 consolidated balance sheet with Actel’s July 4, 2010 unaudited condensed consolidated balance sheet. The unaudited pro forma condensed combined balance sheet gives pro forma effect as if the Actel acquisition had been completed on October 3, 2010.

The unaudited pro forma condensed combined statement of operations combines Microsemi’s consolidated statement of operations, adjusted for the pro forma impact of our acquisitions of White Electronic Designs Corporation (“White Electronic”), VT Silicon and Arxan Defense Systems, Inc. (“ADS”), for the twelve months ended October 3, 2010 with Actel’s unaudited condensed consolidated statement of operations for the twelve months ended July 4, 2010. The acquisitions to White Electronic, VT Silicon and ADS occurred on April 30, 2010, September 10, 2010 and September 14, 2010, respectively. The unaudited pro forma condensed combined statement of operations gives pro forma effect as if all acquisitions had been completed on September 28, 2009.

The pro forma information presented is for illustrative purposes only and is not necessarily indicative of the financial position or results of operations that would have been realized if the acquisitions had been completed on the dates indicated, nor is it indicative of future operating results or financial position. The pro forma adjustments are based upon currently available information and certain assumptions that Microsemi believes are reasonable under the circumstances.

A final determination of fair values relating to the Actel acquisition may differ materially from preliminary estimates and will include management’s final valuation of the fair value of assets acquired and liabilities assumed. This final valuation will be based on the actual net tangible and intangible assets of Actel that existed as of the date of the completion of the Actel acquisition. The final valuation may materially change the allocation of the purchase price, which could materially affect the fair values assigned to the assets and liabilities and could result in a material change to the unaudited pro forma condensed combined financial statements.

These unaudited pro forma condensed combined financial statements should be read in conjunction with the historical consolidated financial statements and related notes contained in the annual, quarterly and other reports filed by Microsemi, Actel and White Electronic with the Securities and Exchange Commission.

MICROSEMI CORPORATION

UNAUDITED PRO FORMA CONDENSED COMBINED BALANCE SHEET

AS OF OCTOBER 3, 2010

(in thousands)

The total estimated consideration as shown in the table below is allocated to Actel’s tangible and intangible assets and liabilities based on their estimated fair values as of the date of the completion of the transaction. The preliminary estimated consideration is allocated as follows (in thousands):

A final determination of fair values relating to the transaction may differ materially from preliminary estimates and will include management’s final valuation of the fair value of assets acquired and liabilities assumed. This final valuation will be based on the actual net tangible and intangible assets of Actel that existed as of the date of the completion of the transaction. The final valuation may materially change the allocation of the purchase price, which could materially affect the fair values assigned to the assets and liabilities and could result in a material change to the unaudited pro forma condensed combined financial statements.

The fair value of the identified intangible assets was estimated by performing a discounted cash flow analysis using the “income” approach. This method includes a forecast of direct revenues and costs associated with the respective intangible assets and charges for economic returns on tangible and intangible assets utilized in cash flow generation. Net cash flows attributable to the identified intangible assets were discounted to their present value at a rate commensurate with the perceived risk. The projected cash flow assumptions considered contractual relationships, customer attrition, eventual development of new technologies and market competition.

The useful lives of completed technology rights are based on the number of years in which net cash flows have been projected. The useful life of backlog is estimated based upon the fulfillment period. The useful lives of customer relationships are estimated based upon the length of the relationships currently in place, historical attrition patterns and natural growth and diversification of

other potential customers. The useful life of the trade name was estimated based on the period in which a benefit could be ascribed to the Actel trade name.

Assumptions used in forecasting cash flows for each of the identified intangible assets included consideration of the following:

The preliminary allocation of purchase price resulted in the allocation of an incremental $132.8 million to goodwill. The factors that contributed to a purchase price resulting in the recognition of goodwill include:

MICROSEMI CORPORATION

UNAUDITED PRO FORMA CONDENSED COMBINED STATEMENT OF OPERATIONS

FOR THE TWELVE MONTHS ENDED OCTOBER 3, 2010

(In thousands, except per share amounts)