Fitch believes an insured loss of more than $50bn would reduce capital levels throughout the rating agency's monitored universe of reinsurers to such an extent that they would attempt to increase premium rates across their entire portfolios.
A loss of this size would also be likely to trigger a negative rating outlook for the reinsurance sector as a whole.
Renewals in July are predominantly related to US exposure, but pricing movements are likely to follow the same trends as the April renewals period, which is more focused on Asian markets.
Figures from Munich Re ('AA-'/Stable) on Tuesday revealed a 35% increase in Japanese earthquake reinsurance prices in April, while relatively flat pricing in other regions and sectors limited the overall increase in prices to around 5%.
Other reinsurers including Scor ('A+'/Stable), Swiss Re and Hannover Re ('A+'/Stable), and the major global reinsurance brokers have reported similar trends.
Fitch says: "We expect to see pricing on US wind-exposed reinsurance programmes rise in the July renewal period, due to near-record tornado-related losses in 2011.
"Property reinsurance prices, which exclude wind-related damage, are likely to achieve, at best, low single-digit price increases.
"Pricing in markets that have already experienced big increases, such as New Zealand property, are likely to rise further, although the increase will not be on the same scale as the 100% rise in 2011.
"We will also closely monitor casualty pricing, which was flat in the April renewal period.
"Casualty reinsurance can be particularly challenging in a protracted period of relatively high inflation and low investment yields.
"This is because claims can arise many years after the cover was written, resulting in payouts that are significantly boosted by inflation over the intervening years and are not offset by investment returns.
"A marked upturn in casualty pricing is only likely to occur when development of reserves from prior underwriting years return to a deficit."