In the weeks leading up to Moody's downgrade of major global banks, corporate treasurers quietly accelerated their own reviews of where to put their bank deposits, who they trade swaps with and who they borrow from.

On Thursday, their caution was validated, as Moody's Investors Service downgraded the ratings of 15 banks, with the deepest hits taken by Bank of America, Citigroup, Morgan Stanley and Royal Bank of Scotland.

Some treasurers had prepared by adding more banks to their credit facilities to diversify the risk of a Lehman Brothers-like bank failure. Some also adjusted their deposit relationships.

Banks, for their part, had been reaching out to treasurers both offensively and defensively, trying to keep clients and win new business ahead of potential turmoil from Moody's review.

"They occasionally mention that they don't know how Morgan Stanley or someone is going to survive," said Nicholas Bijur, treasurer of PG&E Corp, the San Francisco-based gas and electric company. "All the banks call me all the time to tell me what great shape they are in."

Bijur, a former Morgan Stanley employee, said he does not believe that any of the 19 banks in the utility company's $4.2 billion credit facility are at risk of going under, including some European ones. "It is an opportunity, though, to be more critical of their credit quality," he said.

Morgan Stanley chief executive James Gorman said before the announcement that the downgrade of two to three notches that Moody's had telegraphed would be undeserved but "manageable." The company and its bank subsidiary were clipped two rungs to three steps above junk status.

The ratings agency cut Citigroup Inc and Bank of America Corp to just two steps above 'junk' status.

Kim Leary, director of finance at Honeywell International Inc, said the conglomerate regularly revises its investment, trading and bank guidelines based on credit ratings and other criteria.

Honeywell, which had $36.5 billion of 2011 revenue, in April replaced some players in its 29-bank, $3 billion revolving credit facility.

"We have done a lot to prepare and are always thinking of what's next in managing our banks," she said.

"If we feel there is no path forward, or there is too much concentration, we work to transition them out. We're still tweaking because we have some Italian banks we're not too comfortable with."

Honeywell has no corporate bylaws prohibiting it from doing business with low-rated companies, and sometimes differs with views of rating agency analysts, Leary said. She also said she takes trash-talking by rival banks with a grain of salt.

When Bank of New York last summer threatened to charge large companies for deposits, it became "the butt of the jokes of all the other bankers who came in to see us," she said. Honeywell does not keep deposits with Bank of New York.

Some companies said they were carefully monitoring the downgrades but had not taken any action before the expected Moody's announcement.

"We have limitations prescribed by our investment policies on working with banks below certain ratings," said the treasurer of a $3-billion midwestern consumer products company who asked for anonymity. The company was in 'wait-and-see mode' before the downgrades.

A perverse effect of a downgrade, he said, is that it could inhibit the company's efforts to find more large multinational banks in its lending group in order to mitigate risk.

When Lehman Brothers filed for bankruptcy in September 2008, it sent corporations such as PG&E and Sunoco Corp scurrying to find replacements in their bank groups.

Lehman, in return for getting investment banking assignments, represented more than 10 percent of some companies' revolving credit lines. A revolving credit line allows a company to borrow up to a maximum limit after repaying an earlier loan.

Many companies at present include 'yank a bank' provisions in their credit agreements that allow them to replace at will banks in danger of reneging on a loan, bank line or other commitment.

"It's one thing everyone is focused on since the financial crisis," said Thomas Deas, chairman of the National Association of Corporate Treasurers and treasurer of FMC Corp, a Philadelphia-based chemical manufacturer.

The downside of such provisions is that replacement banks aware of a company's desperation may charge higher rates or include more restrictive clauses in a loan agreement, he said.

Another major concern for treasurers is that a bank company or its subsidiary whose long-term rating slips below A2 suffers a downgrade in the short-term rating it issues to guarantee companies' commercial paper and in deposit ratings.

Deas said some companies may adjust their investment policies to allow for lower-A ratings to qualify banks that back their short-term financings.

However, the Moody's review put corporations on general alert. "The riskiness of banks is something treasurers are worried about," he said.

"With these historically low interest rates it's one reason why we are borrowing less from banks and getting funding from the public bond market."