You need to be a pretty weird person to get any pleasure from looking at brokerage statements. Looking at a collection of handbags, on the other hand? To a lot of people, that sounds a lot more attractive. And those people got some good news this week, when a company named Baghunter declared that buying a Birkin handbag is a much better investment than putting your money into stocks.

The Baghunter “study” (we’ll get to the purported numbers in a minute) was soon picked up by uncritical sites like Newsweek, which called the bag “a foolproof investment,” and Luxury Daily, which said that “unlike the S&P 500 and gold, the value of Birkin handbags has never decreased and has steadily and consistently increased.”

There are a lot of problems with this, but let’s start with the most obvious one, which is that the mathematics is simply false. Between 1980 and 2015, says Baghunter, the price of a Birkin bag has gone up by 500%, from $2,000 to $12,000. That’s true. But then they say that on average, the Birkin bag has risen by 14.2% a year over 35 years.

The 14.2% number is just 500% divided by 35, and you can’t do that. If you bought a bag in 1980 for $2,000 and that bag increased in value by 14.2% for 35 years, then by 2015 the value of the bag would be $208,614, not $12,000.

So what’s the real rate of appreciation? If the value of a bag goes from $2,000 to $12,000 in 35 years, then it has actually only gone up by 4.7% a year, on average. Far from being a higher return than you see in stocks, it’s much lower.

For proof, just look at what would have happened to your money if you’d invested $2,000 in the S&P 500 at the end of 1980, and then just kept it there, with dividends reinvested, through the end of 2015. You would have ended up with $75,767 – enough to buy you half a dozen $12,000 Birkin bags, with $3,767 left over for all the events you might want to show them off at.

Meanwhile, what would you have if you spent $2,000 on a brand new Birkin bag in 1980? Well, you’d have a 35-year-old handbag, which quite possibly would be worth much, much less than $12,000. Sure, it might cost $12,000 to buy a new Birkin bag today. But that doesn’t mean that there’s a huge number of people wanting to buy the oldest Birkin bags they can find. *Some* Birkins, to be sure, sell for enormous sums on the secondary market. But that doesn’t mean they *all* go up in value.

Ultimately, there is nothing all that special about a handbag, as Lady Bracknell knew all too well. Handbags are not a good investment, and never will be. My advice: if you want a Birkin bag, spend a couple of hundred dollars on a high-quality fake replica, and put the rest in an S&P 500 index fund. In 35 years’ time, it’ll be worth much more than any handbag you might have been able to buy.