Affymetrix Inc. positioned itself to become one of the elite class of blockbuster IPOs, filing to sell 5 million shares at $11-$13. If the deal gets sold at $12, Affymetrix would have a market cap of $253 million. At that valuation, the Affymax N.V. spinout would join Millennium as the recent ambitious IPOs.

Millennium's offering, filed last month, aims to come in with a market cap of about $223 million. At that size, their peer group would include ICOS (ICOS) and Myriad Genetics (MYGN) among others (see chart). In the related enabling technology/drug discovery segments, some comparison points would be Human Genome Sciences (HGSI, $718 million), Houghten (HPIP, $132 million), Incyte (INCY, $294 million), Pharmacopeia (PCOP, $240 million), and Sequana (SQNA, $165 million).