Fidelity provided what appears to be good news on the retirement front, stating that its average 401k account balance clocked in at $80,600 at the end of the second quarter — a 10% increase from the year-ago period.

Sorry to drizzle on the parade, though, but that’s not as positive as it sounds.

While no statistics were given about what part of that gain came from people putting more money away from retirement, what we can say is that the S&P 500 was up 18% in that time. So even though those balances didn’t grow fatter at the same pace as the market, it’d be a safe assumption that was the primary driver of those bigger accounts — not contributions.

Of course, we don’t need to do the math ourselves to know that contributions weren’t exactly up to snuff. Fidelity’s James McDonald calls out the culprits, saying, “While it’s a good sign some workers are increasing their savings for retirement, many younger workers — especially millennials — aren’t saving at the recommended 10% to 15% of their income.”

There’s also likely some other culprits at play. For one, asset allocation probably had a large effect — any more conservative investors that weren’t heavily in stocks and instead had significant weightings in bonds likely got burned by debt’s returns over that time. Not to mention, many of the managed funds still used in most 401k accounts have much greater expenses than those of their passive counterparts, so some of that money was trickling to managers.

I’m thrilled — as I’m sure most of the people with 401ks run through Fidelity — that those account balances have ballooned.

But clearly it’s far from a perfect situation.

Want more information? Read the Fidelity press release.

Marc Bastow is an Assistant Editor at InvestorPlace.com. As of this writing he does not hold a position in any of the aforementioned securities.

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