Including last week's follow-on notices, at least six companies have tapped the public markets twice over the past year: Fuisz (FUSE), Matrix (MATX), Neoprobe (NEOP), OraVax Inc. (ORVX), PathoGenesis (PGNS), and Sequana (SQNA).

The 2.75 million shares MATX sold last week brings to 7.85 million the number of shares the company has floated in less than a year. But the share price continues to ignore the dilution (see chart). Since the placement of 1.5 million shares at $12 on July 24, 1995, MATX has climbed 98 percent to close last week at $23.75. On Oct. 16, 1995, MATX raised $47.7 million through the sale of 3.6 million shares at $13.25, and last week it raised $62.2 million through the sale of 2.75 million shares at $22.63.

Four of the companies are chasing their IPOs: FUSE raised $33 million in its December IPO and last week filed to sell 3 million shares, of which the company will offer 750,000. ORVX went out in June and last week filed a 2