If I had a nickel for every error on Yahoo, I’d have hundreds of thousands of dollars’ worth of coins. Missing apostrophes, like those on Yahoo Finance, would contribute to my stash:
Sometimes a word ending in S looks like a plural, but it’s really a quasi possessive. This is a case of a quasi possessive. (It’s also an example of the genitive case, which is more grammar than I like.) If you’re unsure whether you’re faced with a simple plural or a quasi possessive, try this: Substitute the number 1 for the number in the phrase. So, instead of “millions of dollars worth,” try “one dollars worth.” Notice that I used dollars, and not dollar, because that sounds right to me. But of course it’s not a plural, so it must be a possessive: one dollar’s worth. This method depends on having an “ear” for correct language, something Yahoo writers seem to lack.