Analysts said the market would be watching closely how the Treasury Department structured its planned purchases of troubled assets from financial firms. The government has suggested it might use auctions to establish prices for the securities and loans it plans to acquire. Mr. Zandi said the Treasury should disclose more details in the next several weeks and conduct its first auctions soon after the presidential elections.

Once investors have a better sense of what the troubled assets are worth, they will become more willing to invest in ailing financial firms that have not been able to raise capital because analysts fear they have not fully disclosed the quality of their assets.

“We need to get clarity with respects to which institutions need to write down their assets and which institutions are well-capitalized,” Mr. Zandi said. “That would provide solace to investors who would then provide capital to the system.”

Furthermore, once financial firms have raised more capital, a crucial test will be whether they plow that new money back into the market through loans and investments in businesses, said Mr. Webman. If banks remain fearful and hoard cash instead, as they have done in recent months, the rescue effort will only have a modest impact on the economy and financial system.

“We need more capital coming into the market and actual investor money coming through the banks into economic activity,” Mr. Webman said. “That’s what I would really like to see happen.”

But even if the government intervention is successful, economists and investors said it would not restore the days of easy credit that prevailed during the recent housing boom. Mortgage rates should come down, but they are unlikely to return to the levels seen in 2003 and 2004. Also banks are unlikely to make many adjustable-rate loans without verifying the incomes and assets of borrowers.

Furthermore, the rescue might not forestall a recession, said G. David MacEwen, chief investment officer for the bond department at American Century Investments. Though he thinks the rescue efforts will help the economy, Mr. MacEwen expects bankruptcies to spread, home prices to fall and unemployment to rise.

“Having this plan contains the damage to some extent,” Mr. MacEwen said. But, he added, “I think we are going to see slowing in economic activity. This is like steering a battleship, you make course adjustment but they take time to take effect.”