Yahoo is losing yet another top executive–Toby Coppel, its EVP and managing director of Europe and Canada, is set to announce today that he is stepping down.

The departure, which has been in the works for months, is not related to the recent news that Yahoo CEO Jerry Yang is also relinquishing his job as soon as the company completes its search for another CEO.

Coppel’s job covers the major Western European markets (United Kingdom, France, Germany, Italy, Spain, Scandinavia), as well as Canada, for Yahoo (YHOO).

His successor will be Rich Riley, who is currently SVP of Europe’s Advertiser & Publisher Group, which put him in charge of all revenues for the division. Riley, who came to Yahoo a decade ago, was previously the head of Yahoo’s Small & Medium Business Group in the U.S.

Coppel, who came to Yahoo with former Yahoo CEO Terry Semel in 2001, has run European operations for Yahoo for 18 months. And most of his time has been spent restructuring and making massive cuts.

The unit will have about one-third of the people as when Coppel arrived by the first quarter, after the current round of layoffs. And, if you include Yahoo’s sale of the comparison-shopping site Kelkoo last week, the cuts total 45 percent of its former size.

Coppel also shepherded the move of Yahoo’s European HQ to Switzerland from higher-priced London. Most of its top managers are now located there, although London remains an important Yahoo outpost, since it is the largest online ad market in Europe.

Coppel will remain with Yahoo until the end of the first quarter to ensure a smooth transition. He told BoomTown in an interview that his future plans are undetermined, except to welcome his third child into the world very soon.

“I have been transitioning our European business, restructuring it and making it stronger, as Yahoo is moving to product development on a global platform,” said Coppel. “While there is more work, there is now a strong team in place, focused on going forward and it needs to spread its wings.”

Coppel noted, although a lot of his tenure was occupied by restructuring the European unit, that “we have taken display advertising market share from MSN, AOL and other competitors in almost every one of our European markets in 2008 and we grew our Canadian business over 50 percent this year.”

And, indeed, Yahoo’s online display advertising business is stronger in Europe, although subject to the same vicious economic downturn that has hit the U.S. market.

In addition, Yahoo–and everyone else–lags well behind Google (GOOG) in the more lucrative search business in Europe, even more so than in the U.S., forcing competitors like Yahoo to streamline to compete.

That has meant layoffs, but also re-architecting Yahoo’s product development toward a global model to cut costs and also getting rid of some noncore assets like Kelkoo.

It was revealed last week that Kelkoo was sold to a U.K.-based private equity firm called Jamplant, at a reported discount from what Yahoo paid for it–$576 million–in 2004.

Now that all these kinds of major changes were made, Coppel said, it seemed a good time for him to go too.

“My value add-was not what it was going forward,” said Coppel, who noted that several layers of management in Europe had been collapsed in his tenure. “If we are streamlining and we mean it, it has to also start at the top.”

BoomTown was a squeaky enough wheel to get Yahoo CEO Jerry Yang to grant a long interview by phone yesterday–just a day after he had announced weak third-quarter earnings results for the Internet giant, caught as others are in the econalypse, as well as layoffs of at least 10 percent of its global workforce.

But instead of being glum, as you might expect, especially after a year of corporate turmoil that would have finally gotten to even Job–let’s review: management upheaval, a Microsoft (MSFT) takeover battle, an attack by billionaire activist Carl Icahn, tangling with the Justice Department over a pending Google (GOOG) search advertising partnership and more!–Yang sounded surprisingly confident that Yahoo (YHOO) would emerge a winner after all the wrenching change is wrought at the company he co-founded.

I split the interview into two parts. The second will appear later today at 4 p.m. Pacific time, talking about Icahn, the Google deal, Microsoft and why Yang thinks he is the right leader for Yahoo, so check back.

Here is the first part, in which he talks about Yahoo’s financial performance and the impact of the bad economy on Yahoo’s dominant display advertising business and gives more details of the layoffs and cost cuts.

BT: How do you look at the last quarter?:

Yang: What we said was that the quarter showed some strength in U.S. search and performance display, but more weakness in branded, especially at the end in the U.S., and more so internationally. The U.S. started softening in Q2 and that continued into Q3. International was hit much harder, although display still grew double-digits there in Q3. Softness started in the U.K. early, and we knew when the French came back from vacation in September and did not buy ads at the same levels that those were trends we had to watch.

Asia was more of a surprise, but the same trends were happening there too. Because we have such a big market share there, we are looking to every country for what is coming next.

BT: And what is your Q4 outlook?:

Yang: Like everyone else, we are pretty much forced to formulate our views in an unprecedented set of circumstances because things are changing so quickly and the world looks a lot different than just three or four weeks ago.

Of course, I can’t imagine advertisers are going to say we’re going to juice up spending soon, and so we’re assuming a lengthy period of weakness. I don’t think anyone is going to be immune, even though search performance ads are probably more able to withstand a downturn in spending. What was good for us was that our search and our performance display businesses were both up in the quarter.

BT: Any more details about the layoffs and other cuts?:

Yang: We want to do it before the holidays, which is why we wanted to let people know that it would affect 10 percent [of Yahoo's work force]. But we also want to make sure that we are cutting to be more effective and not cutting for cutting’s sake.

We’re asking ourselves–should we sell it or should we shut it down? That is the kind of comprehensive look we are doing across the company.