Bad Share Day: Yahoo Stock Limp After Investor Day (and Google’s Swiping of Its Ad Title)

Apparently, reassurances about its relationship with Chinese partner Alibaba Group and some lively presentations by top execs at a six-hour investor day yesterday did almost nothing for Yahoo shares.

The stock of the Silicon Valley Internet giant continues to stay mired on either side of $16 a share today, as it has been since it got into a very public fight with Alibaba over the spin-out of its Alipay online payments unit.

Alipay got its license from the People’s Bank of China today, due in part to moving the unit to the ownership of Alibaba founder and CEO Jack Ma, but that also did squat for Yahoo shares.

Also dragging the stock down: An IDC report released today that shows that Yahoo has lost its number-one display advertising title to Google. The search giant’s share of that market in the U.S. rose to 14.7 percent in the fourth quarter of 2010, while Yahoo’s declined to 12.3 percent.

That’s not good news, even though both Yahoo’s Chief Product Officer Blake Irving and its U.S. media and advertising head Ross Levinsohn both gave energetic presentations at Yahoo’s investor day yesterday.

The two execs–one sporting a natty blazer and the other his patented hair-tastic ’do–trotted out a lot of can-do stats and fancy plans for the audience, which was mostly preoccupied with Yahoo’s China problem.

In contrast, CEO Carol Bartz, CFO Tim Morse and co-founder Jerry Yang were mind-numbingly rote on that thorny issue, noting that negotiations with Alibaba were ongoing and would remain private.

(As if–if I have anything to say about it!)

Bartz told the group of investors and Wall Street analysts yesterday that Yahoo “really believe[s] we are working towards protecting the value of Alibaba Group. The emphasis is on discussion. [We’re] not going to get into a public back-and-forth.”

Having already done that in a ham-handed way the week before, that’s probably a most excellent idea for the shoot-from-the-hip exec.

In any case, investors don’t seem to want to take Bartz’s word for any of it until she delivers–both a China solution and, more importantly, turbocharging of both its core search and display advertising businesses.