Today, Yahoo shares plummeted almost nine percent to close at $10.34, off $1.01, in yet another freefall that has all sorts of disturbing implications for the troubled Internet company.

For one, it makes the merger possibilities with Time Warner (TWX) online unit AOL that much more difficult.

Yahoo’s market cap is off another billion dollars to $14.3 billion right now, and that has a big impact on how much it can pay to own AOL. If at all, that is.

In addition, the options of Yahoo (YHOO) employees are so under water as to be Atlantis, which is sure to make it harder–even in this weak economic environment–to retain and attract talent.

At the very least, it creates a very gloomy Yahoo corporate campus in Sunnyvale.

And while shares of all tech giants were off yesterday, part of the continuing worry about the advertising market online, Yahoo’s drop was significantly more than the others.

It reflects a deep worry among investors about the prospects of its current leadership under CEO Jerry Yang to pull off a much needed turnaround.

If Yahoo shares drop below $10 a share (remember the halcyon days only a few months ago, when the $20-a-share Rubicon was scary?), it creates a very ironic situation.

That being that the company is a true bargain for a buyer interested in scooping up one of the Internet’s still most-trafficked properties, except that not many have the wherewithal in this financial meltdown to pay up.

Except, of course, for Microsoft (MSFT), which has expressed so much disinterest in buying Yahoo as to be pathological about it.

Instead, in its continuing obsession with messing with archrival Google (GOOG), it focuses on overpaying copiously for a search deal to get on the mobile phones of Verizon (VZ).

But at a $10-or-less price tag for a business that could still turbocharge his company’s even less impressive online search and advertising efforts, isn’t it time Microsoft CEO Steve Ballmer got some therapy to get over his Yahoo issues?