M&A professionals believe the deal environment is showing signs of improvement, according to a survey.

Total announced merger and acquisitions activity totaled $480.3 billion in the first quarter of the year -- down 28% from the first quarter of 2008, according to the survey by the Association for Corporate Growth and Thomson Reuters.

Major deals include

Sun Microsystems'

(JAVA)

planned $5.6 billion sale to

Oracle

(ORCL) - Get Report

;

Pfizer's

(PFE) - Get Report

purchase of

Wyeth

(WYE)

for $68 billion; and

Merck's

(MRK) - Get Report

$41.1 billion purchase of

Schering-Plough

(SGP)

.

Fifty-six percent of the 703 investment bankers, attorneys and other dealmakers who participated in the survey say the number of mergers and acquisitions will increase over the next six months, while just 10% predict fewer deals.

Despite optimism about the future, the survey, which is conducted twice a year, is more negative than ever in its history in assessing the present situation. Eighty-eight percent of respondents say the current M&A environment is fair or poor, compared with 86% who said the same thing in December.

The main reason for the reduced deal activity is the lack of available credit, according to the survey. As

TheStreet.com

recently noted, some large

private-equity

firms have responded to the credit crunch by buying distressed debt.