“Put all your eggs in one basket–and watch that basket!”

A few advisory firms–Lazard, Evercore, Greenhill and Blackstone Group–emerged from the dark M&A downturn of 2000 to 2003 heeding that age-old advice from Andrew Carnegie. Still, even these guys said they were preparing for a day when M&A would fall and were building more baskets and expanding more-stable businesses like restructuring, asset management and private equity. Well, with M&A activity having dried up since the credit crunch hit in June, how’s that going?

The boutiques actually aren’t doing badly in the M&A business, mostly because they aren’t at the mercy of private-equity-firm deals. While large banks such as Goldman Sachs Group, J.P. Morgan Chase and Deutsche Bank built large efforts focused on advising and financing private-equity firms, many boutiques stuck with old-fashioned “strategic buyers,” the Wall Street term for companies. And given the relatively small size of these businesses, it doesn’t take a lot of assignments to keep their head above water.

Greenhill, for instance, has four big mandates expected to close this quarter, including an $11.4 billion assignment for U.K. water company Kelda; a $4.6 billion deal for Nikko Cordial on its proposed share exchange with Citigroup; a $3.4 billion deal for Ventana by Roche Holdings; and a $3.4 billion deal for American Financial Realty Trust by Gramercy Capital. Wachovia analysts predict Greenhill may win roles on another $12 billion to $15 billion of deals this quarter, including the firm’s assignment for Delta Air Lines, which seeks to combine with Northwest.

Meantime, Moelis & Co., founded last year by former Donaldson Lufkin & Jenrette star Ken Moelis, is advising on Yahoo’s defense against the Microsoft takeover offer, while Blackstone has an advisory credit on the Microsoft side. Moelis also is advising Westwood One and Entravision on much smaller, $100 million deals. Blackstone is advising Northern Rock on the $4.4 billion sale of a mortgage portfolio to J.P. Morgan.

Then there is Lazard, which not only has found a place on the biggest deal extant, BHP Billiton’s proposed $150 billion combination with Rio Tinto, but also on Gaz de France’s 45-billion-euro merger with Suez and Trane’s $10 billion sale to Ingersoll-Rand. It also advised China Investment Corp. on its investment in Morgan Stanley and the Kuwaiti Investment Authority for its investment in Citigroup.

Sure, the deals are not many and they are not huge (with the exception of Microsoft-Yahoo and BHP-Rio, of course). A volume business, this isn’t. Still, they are big enough to be moneymakers, and without elaborate debt financing involved, have a better chance of closing than your average leveraged buyout. A surprising number also are international; while you would expect Lazard, with its European roots, to do well overseas, Greenhill and Evercore also frequently look outside U.S. borders. In fact, while Lazard drew a little more than 50% of its revenue from foreign deals last year, Greenhill drew even more, or about 64%, of its advisory revenue from clients outside the U.S., according to the firm’s latest annual report. That isn’t even counting big potential paydays like the $32.6 billion buyout of BCE, a Greenhill client.

Still, the boutiques have diversified. Goldman Sachs research analysts said of Lazard last month, “The firm has never been in a stronger position, in our view.” Lazard’s advisory revenue last year was a record $1.25 billion, up from $973 million in 2006 and constituted the vast majority of the firm’s total $2 billion in revenue. More importantly, its asset-management revenue jumped 31% to $717 million. The firm’s restructuring bankers are working on deals advising Adelphia Communications, SunCom Wireless, Eurotunnel, Tower Automotive, InSight Health Services, New Century Financial Corp. and the Northwest Airlines Creditors Committee.

Some boutiques have a ways to go: While Greenhill had a record year, with 33% growth in advisory revenue, it still is highly concentrated in advisory work; $366.7 million of its revenue came from merger advice, while only $33.7 million came from their own private-equity investments. That compared with $209 million of advisory revenue and $80.8 million in revenue from PE investments last year.

Mr. Market isn’t showing much faith in these firms, as skepticism reigns over financial stocks. Lazard’s shares are down nearly 30% in the past year. Evercore’s are down nearly 40%. Greenhill’s are down about 3%. Life’s tough in the big leagues.