Or at least half new.
50% of Yahoo shares have changed hands over the last four days.
Ironfire Capital fund manager Eric Jackson says that Yahoo's average ownership turnover over four days is closer to 8%.
Here are some theories as to what's going on:
Yahoo is probably buying a bunch of its own stock. Yahoo had a big stake in Alibaba, and sold 121 million shares during its Friday IPO. Yahoo management promised that it would use half the after-tax proceeds to buyback Yahoo shares. That would account for ~$3 billion of the $20 billion changing hands.
People are probably selling Yahoo and buying Alibaba. For a long time, Yahoo stock was going up because owning it was just about the only way you could gain exposure to Alibaba. But now Alibaba is a public company. So people who owned Yahoo for Alibaba are probably now selling it and buying Alibaba.
Yahoo is a juicy acquisition target. It has a ton of cash and owns big chunks of two Asian companies: Alibaba and Yahoo Japan. If you add up the value of that cash and those stakes, the number is actually bigger than Yahoo's market cap. That means Yahoo's core business, which generates nearly $5 billion in revenues every year and nearly $1 billion in profit, is being valued at close to $0 by the market. It's likely that some arbitrage fund managers are buying into Yahoo, hoping some kind of transaction goes down.
Value investors believe that Yahoo is undervalued and want to bet on Marissa Mayer. It's possible that some value investors are looking at Yahoo's sum-of-the-parts valuation, seeing how little the market values the core, and buying Yahoo stock because they believe CEO Marissa Mayer will soon have the company growing again. Truthfully, all she has to do is get revenue growing again, and the market will probably apply the same multiples to Yahoo as they do to Microsoft and AOL - two other tech companies in turnaround. Right now, that would mean a boost in Yahoo's stock price. Maybe some people with money are betting that Mayer can clear a really low bar.
Yahoo is a juicy acquisition target, part two. If one of the two companies that Yahoo owns big stakes of, Alibaba or Yahoo Japan, were to buy Yahoo, they would be able to realize the full value of Yahoo's stake in themselves without having to pay taxes on it. That's another reason arbitrage investors might be buying in.
Some activist could be building a stake. There is an argument to be made that Marissa Mayer is doing a poor job managing Yahoo. She could cut costs by slashing headcount. She could outsource its display business to Google. Maybe there is an activist out there who thinks the market would give Yahoo's core business a greater valuation if he or she could buy a bunch of Yahoo stock and force Mayer to make a few quick changes.
If anything really dramatic is happening, we'll know soon because you can't buy more than 5% of a public company without disclosing it.
Nicholas Carlson is the author of Marissa Mayer and the Fight to Save Yahoo! on sale January 6, 2015.