A series of transactions hitting the market is expected to generate roughly $400 million in additional catastrophe bond capacity, and veteran sponsors are taking the lead, experts say.

Zurich, Switzerland-based Swiss Reinsurance Co. is in the process of placing a one-year cat bond to cover California earthquake and North Atlantic hurricane exposures, according to Standard & Poor’s Corp.

While S&P’s presale report did not include a collateral value for the bond, Successor X Ltd. is expected to be a $60 million deal, market sources said. However, strong investor appetite could boost the bond closer to $100 million before the transaction closes at the end of November, several investors said.

New York-based S&P assigned a preliminary rating to the bond of B-.

Separately, Swiss Re also is in the process of placing a $75 million mortality bond, Vita Capital IV Ltd., to protect itself from higher-than-expected mortality rates through Jan. 1, 2013, market sources confirmed.

The transaction—driven in part by fears of the H1N1 flu pandemic—aims to replace Swiss Re’s Vita Capital II Ltd. mortality bond, which is to mature in January 2010, market sources said. The deal, upsized from its $50 million target, is expected to close next week, sources said.

Meanwhile, Hamilton, Bermuda-based based Flagstone Reinsurance Holdings Ltd. is preparing to issue a $120 million cat bond to protect it from U.S hurricanes and earthquakes, market sources confirmed. The three-year bond, Montana Re Ltd., is being marketed to investors and expected to close in December.

In addition, Paris-based SCOR S.E. is preparing to issue a cat bond to cover its exposures to European windstorms, market sources confirmed. The transaction is expected to reach the $100 million range and is likely to close by Dec. 1, sources say.

Experts say additional European windstorm deals could come to market by year-end ahead of the start of the European windstorm season, which begins Dec. 1.

If successful, the transactions would bring the insurance-linked securities market close to the $3 billion to $4 billion experts anticipated for 2009. Year-to-date issuance stands at $1.79 billion, according to data from New York-based Guy Carpenter & Co. L.L.C. and GC Securities, units of Marsh & McLennan Cos. Inc.

Last month, experts predicted the fourth quarter would be active in terms of issuing cat bonds, citing a strong pipeline of potential deals. Renewed interest by insurance companies in issuing the bonds is being driven, in part, by a significant drop in cat bond pricing due to investors’ greater willingness to accept lower returns on the bonds.