Once upon a time Vanguard did have a preferred stock mutual fund, but it was closed and liquidated in 2001.
It's funny, you never hear about preferred stock any more. Apparently it is sort of an historical curiosity at this point and not used except by... what was ValueThinker saying... a few financial companies as part of some complicated strategy. In addition to what Larry says, from my own naïve point of view I've just filed it away as "weird stuff I don't need to know about." And as part of the "neither fish, flesh, fowl nor good red herring" stuff, the stuff that's in between stocks and bonds, your safer stocks and your riskier bonds. The burden of proof is always on the person who claims that there's something magically wonderful about these chimeras that makes them far better somehow than just adjusting the balance between plain old stocks and plain old bonds to get the risk you want.
When I was a kid, though, in the 1950s and 1960s, ordinary financial discussions usually used the phrase "common stocks," not just "stocks," because preferred stocks were, uh, common enough that it was important to be clear about what you were talking about. I have no idea why, but all the stuff targeted at novices and laypersons ALWAYS made a point of explaining the difference. When I was in, was it sixth grade, and went on a field trip to New York to visit the Morgan Library and the Stock Exchange, the guide explained the difference between preferred stocks and common stocks. I remember that. I remember the Gutenberg Bible in the Morgan library. I remember a conference room at the NYSE that had the most amazingly thick carpet I have EVER seen, it really seemed to be four or five inches deep, I mean it was a little hard to walk on it was so thick. Oh, yes, we also visited the Federal Reserve and I was quite impressed by seeing a million dollars in one-dollar bills piled on a fairly ordinary-looking table.
Annual income twenty pounds, annual expenditure nineteen nineteen and six, result happiness; Annual income twenty pounds, annual expenditure twenty pounds ought and six, result misery.