Yahoo's stock took a nosedive on Wednesday following another disappointing earnings report. With the company continuing to lose market share in online advertising, investors now say the core business is worth nothing. Actually, less than nothing.

The Sunnyvale, California-based company has a stock market value of $29.5 billion. Add up its $5.5 billion in cash and marketable securities net of debt, $22.6 billion stake in Alibaba, $2.3 billion investments in equity interests (Yahoo Japan) and you get $30.4 billion, or almost $1 billion over Yahoo's market cap.

What about the $950 million in earnings that analysts are projecting for 2015? It's evidently irrelevant to investors, who are rapidly losing confidence in CEO Marissa Mayer's ability to right the ship.

Our math assumes a tax-free spinoff of Alibaba's shares. The IRS recently told Yahoo that it wouldn't rule on whether the company can avoid a tax hit when it puts that stake in a separate entity to be named Aabaco. So shareholders are either factoring in a multibillion dollar tax bill or pricing Yahoo's operations at zero.

Correction: An earlier version of this story misidentified the agency that ruled on the tax status of the Alibaba spinoff.