* Receives $300 mln to settle MBIA suit, still takes 48 mln euro charge
* CEO says environment "less favorable" since mid-March
* Core Tier 1 at 10.6 pct end-March, better than rivals
* CIB pretax profit down 36 pct but up vs Q4
By Matthieu Protard and Christian Plumb
PARIS, May 9 (Reuters) - French bank Natixis posted a less-than-expected 30 percent drop in quarterly earnings on Wednesday as increasing asset management revenues helped offset writedowns on Greek sovereign bonds and an accounting adjustment on its own debt.
Natixis, an investment bank and asset manager controlled by unlisted cooperative lender BPCE, reported first-quarter net profit excluding exceptional items of 339 million euros ($438.4 million), down from 483 million in the year-ago period.
Analysts at Societe Generale had forecast profit at 315 million euros, while Oddo Securities had forecast 231 million.
Revenue fell 4 percent to 1.669 billion euros, the bank said.
Natixis was rescued from near-collapse during the 2008 financial crisis by a government-backed merger of its retail cooperative parents.
It has since cut a swathe through its balance sheet, getting a head-start on the race to build capital that is sweeping across the industry.
The bank's core Tier 1 capital ratio under Basel 2.5 methodology - a key measure of its ability to absorb losses - was 10.6 percent at end-March, higher than those of bigger rivals BNP Paribas and Societe Generale.
Natixis said it had signed an agreement with U.S. bond insurer MBIA Inc in which the bank received $300 million in return for dropping out of a lawsuit challenging MBIA's 2009 restructuring.
The settlement, which will result in a 4.7 billion euro reduction in the BPCE group's risk-weighted assets, still forced it to take a 48 million euro charge against pretax profits.
It also wrote down 19 million euros on Greek debt.
Pretax profit at the bank's core corporate and investment bank fell 36 percent from a year ago but surged 48 percent from a depressed fourth quarter.
Natixis Chief Executive Laurent Mignon told reporters on a conference call that the bank had benefited from "much less volatile market conditions" than in the year-ago quarter but added that the market had been less favorable since mid-March.
Revenues in the corporate and investment bank were down 11 percent to 760 million euros, compared with a strong year-ago quarter, while asset management revenues rose 12 percent to 411 million.
Natixis had the biggest slice of a shrinking market in managing bond issues in the quarter, with $16.1 billion or 15 percent of the market, according to Thomson Reuters data.
The bank's shares have gained 8.1 percent so far this year, outperforming the European sector, which is down 2.2 percent over the same period.
That heady performance, though trimmed drastically over the last month, is a tribute to the restructuring efforts of Chairman Francois Perol, a former aide to President Nicolas Sarkozy, who was drafted in three years ago to drain the lender's swamp of risky toxic assets and better integrate it with unlisted retail parent group BPCE.