The week's winners
GoshawK up 8.5%
Atrium up 8.3%
The week's losers
Domestic & General down 2.5%
Aspen, the Bermuda-based insurer linked with Wellington, is planning to float in New York.
The group reacted to growing speculation by announcing it was planning an initial public offering of shares.
Wellington, which has a 19.8% stake in Aspen, said, along with other shareholders, that it would not sell its Aspen stock in the IPO or for 180 days afterwards.
The exact timing of the float will depend on market conditions, Aspen said.
The number of shares to be sold and their value was also still to be determined.
Aspen was formerly known as Wellington Re. The group was founded in June last year and changed its name in March this year to Aspen.
Its origins were in a £448m capital raising from private equity investors led by Blackstone and Candover and including CSFB Private Equity, Montpelier Re, 3i, Phoenix Equity Partners, Olympus Partners, Lexicon and Wellington Re Management.
GoshawK continues to try to shake off difficulties brought on by insufficient checks and controls on its underwriting.
Standard & Poor's took a gloomy view of its financial strength, following Moody's in downgrading the beleaguered Lloyd's-based insurer.
The group's stock heads up our winners list this week but only after bouncing around in the low 30s. It was trading at 35p on Tuesday, which arguably shows some more confidence among investors than earlier this month, when it sank as low as 24p.
One investor prepared to back GoshawK was Phoenix Asset Management Partners, which took a 6% stake while the stock was languishing.
Could the combination of Phoenix and GoshawK get the insurer back on its feet?