Fortinet ( FTNT - Get Report) shares were taking a breather after trading as high as $16.88 Thursday as the IPO market heats up ahead of imminent offerings from Cloud Peak Energy, Archipelago Learning and Global Defense Technology.

Security specialist Fortinet burst out of the blocks on its first day of trading Wednesday, with shares quickly rising above their $12.50 offering price to close at $16.62.

Fortinet's stock rose 26 cents during Thursday morning trading before retreating to a recent 12-cent, or 0.7%, loss for the day, still outperforming the broader decline in tech shares that saw the Nasdaq fall 2.1%.

Another company making the public leap this week is Cloud Peak Energy. The country's third-largest coal producer is expected to begin trading Friday, according to Scott Sweet, senior managing partner at analyst firm IPO Boutique.

Cloud Peak, which has been carved out of Rio Tinto's western U.S. coal business, is seen as one of the cleaner coal companies. Earlier this week, for example, Jim Cramer pointed to Warren Buffett's recent purchase of Burlington Northern ( BNI) as evidence that the IPO will be successful, describing Cloud Peak as a "sleeper deal."
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The Gillette, Wyo.-based firm has priced its IPO at between $16 and $18 a share, and expects to bring in $491.6 million after expenses.

Online education company Archipelago Learning is also in the spotlight this week and is expected to start trading Friday.

The Dallas-based firm has priced its 6.3 million shares at between $15 and $17. Archipelago aims its services at young children but is going public at a time of shrinking K-12 budgets.

The company, however, is not the only education specialist to IPO this year, following offerings from Bridgepoint Education ( BPI) and Education Management ( EDMC), which tailor their respective technologies at the college market.

Another company in the government sector is also gearing up to go public this week.

Global Defense Technology, which provides IT services to the defense sector, has priced its offering at between $14 and $16 a share. The company is also expected to make its public debut on Friday, according to IPO Boutique's Sweet.

-- Reported by James Rogers in New York