Helicos Biosciences Corp.

Cambridge, Mass. • 617-264-1800 • www.helicosbio.com

Exchange and Ticker: Nasdaq: HLS

Filing Range: 5.40M shares @ $13.00 to $15.00

Offering Price: $9.00

Close on First Day: $8.47

Offering Size: $48.60M

Shares Outstanding: 20,519,975M

Underwriter: UBS Investment Bank

Co-managers: Pacific Growth Equities Inc./ Leerink Swann & Co.

Company Counsel: Goodwin Procter LLP

Manager Counsel: Dewey Ballantine LLP

Auditor: Pricewaterhouse Coopers LLP

Market Capitalization on 5/31/07: $172.37M

Close price at current month end: $8.40

DESCRIPTION

Operates as a life sciences company that develops genetic analysis technologies for the research, drug discovery and clinical diagnostics markets. The company’s first commercial product, the HeliScope, is designed to enable ultra-high-throughput genetic analysis based on the direct sequencing of single molecules of DNA or single copies of RNA. Competitors include the Applied Biosystems division of Applera Corp., Beckman Coulter Inc., the Amersham Biosciences business of General Electric Company, Affymetrix Inc., Agilent Technologies, others.

VENTURE BACKERS

Atlas Venture, Flagship Ventures, Highland Capital Partners, MPM Capital, Versant Ventures.

Source: Thomson Financial