Recent data show that the U.S. personal savings rate has been on its way down.  In other words, consumers have been spending more than they have been earning.

This is one of the reasons why consumer spending has held up.

Some economists warn that this is troubling and unsustainable.

But for now, it's a trend that bolstering the economy.

So, what's behind this?

"Recent data has shown continued strength in consumption, but that strength may come from how consumers "feel" from rising wealth," write the analysts at BlackRock. "The strong inverse relationship between wealth and savings explains the historical erosion in the savings rate."

The drivers of household wealth include rising home and stock prices.

A lot of passive investors in the stock market will soon get their first quarter statements.  Many will probably be happy to see their equity allocations up around 10 percent since the beginning of the year.

Here's the chart from BlackRock:

Chart of the day shows the falling personal savings rate, april 2013BlackRock