Banks that had been preparing to celebrate successful capital raises may want to put their pink champagne back on ice.

A series of acquisitions and securities offerings unveiled earlier this year, some just a few weeks old, may be in jeopardy because of wild stock market swings, according to industry observers.

Capital One Financial Corp. in McLean, Va., and First Niagara Financial Group Inc. in Buffalo, N.Y., are among those that announced big deals dependent on raising more capital.

"Timing is everything," said Damon DelMonte, an analyst at KBW Inc.'s Keefe, Bruyette & Woods Inc. "The capital markets are on edge right now."

Market uncertainty could also delay a number of initial public offerings that banks had lined up earlier this year.

HomeStreet Inc. of Seattle said on Aug. 9 that it would postpone the pricing and closing of a $210 million IPO it had planned.

At least eight other banks have filed registration statements for IPOs with the Securities and Exchange Commission since October 2010.

As of Friday, none of those banks had followed HomeStreet's lead, but they all remain in the holding queue.

HomeStreet may have taken the atypical step of publicly announcing its delay because of the "strange phenomenon" last week of the market's huge swings up and down, said William Fitting, a senior consultant at CCG Catalyst Consulting Group and a former executive at SunTrust Banks Inc.

"The degree of volatility has been the scary part, not the volatility itself," Fitting said.

HomeStreet spokesman Dennis Floyd did not elaborate on the $2.4 billion-asset company's press release.

So far, First Niagara is sticking with plans to raise up to $1.2 billion through equity and debt issuance to finance buying 195 branches from HSBC Holdings PLC.

"Our anticipated transaction-closing timing and the capital plans we announced in connection with the HSBC branch acquisition remain unchanged," First Niagara spokesman Jeff Schoenborn said Friday in an email statement. "We expect to raise capital prior to transaction closing, and the exact timing of the raise will be dependent on market conditions. We said then that the market was not where we would like it to be, and that we would be patient and pick our spot."

The $31 billion-asset First Niagara has plenty of time for the markets to rebound; the company expects to complete the acquisition in the second half of next year.

"They're not overly sensitive to completing a capital raise in the very near term," DelMonte said. "I'd like to think the markets will be more forgiving and we'll see a rebound in the broader markets in the next six months."

Though he did not single out any specific bank, Howard Friedman, a partner at PricewaterhouseCoopers, said he expects companies to try to move forward with their capital-raising plans later this year.

"The companies we're talking to aren't really worried," said Friedman, who works in the accounting giant's capital markets group. "We're seeing the postponing of deals this week, but they haven't withdrawn the deals."

For its deal to buy some of the U.S. credit card businesses of HSBC, the $200 billion-asset company said it needs to raise up to $1.25 billion.

As of Monday, Capital One had not provided an update on its plans, and company spokeswoman Julie Rakes could not be reached for comment.

Capital One has another big acquisition in the works: its deal for ING Direct. It completed a $2 billion offering in July to fund the buyout of ING Group NV's U.S. online bank.

EverBank Financial Corp. last October filed documents to raise $200 million. The Jacksonville, Fla., company had not priced the offering as of Monday. A spokeswoman for the $12.5 billion-asset EverBank did not comment.

Other banks with planned IPOs include Ally Financial Inc., North American Financial Holdings Inc., Bond Street Holdings Inc., Midland States Bancorp Inc. and Circle Bancorp.

Leon Holschbach, the president and chief executive of Midland States, said he could not comment because of the IPO's quiet period. A Circle spokesman did not comment, and executives at the other companies could not be reached for comment.

It is likely that these banks would not have priced their offering this month, since August is a historically slow month for IPOs, Friedman said.

The dizzying swings in the stock market are not just affecting banks. Cathay Industrial Biotech Ltd., for instance, said on Aug. 5 that it would delay its IPO.