What happened

Shares of Brighthouse Financial (BHF -0.84%) stock are down 10.2% as of 10:45 a.m. EDT after Swiss megabanker Credit Suisse downgraded the seller of life insurance and annuities on interest rate and accounting concerns this morning.

Credit Suisse highlighted three separate, interrelated concerns about Brighthouse, as explained today in a write-up on StreetInsider.com.

First, lower interest rates year to date could reduce Brighthouse's "2019-2021 distributable earnings" by as much as $1 billion.

Second, "favorable equity markets" could make up the difference. However, Brighthouse's dependence on a strong stock market saving it from interest rate changes "underscores Brighthouse's sensitivity to markets."

Third and finally, Credit Suisse warns that "new fair value accounting standards for insurance products with market risk guarantees, which include most variable annuities" could reduce Brighthouse's book value.

Tumbling dice read "buy" and "sell."

Image source: Getty Images.

So what

Add it all up, and Credit Suisse, which was previously neutral on Brighthouse Financial stock, now rates the stock an "underperform" with a $22 price target -- 37% lower than its previous price target.

Investors appear to be taking this warning to heart this morning, as well they might. Even leaving aside the interest rate concerns, according to data from S&P Global Market Intelligence, the sale of annuities makes up more than half of Brighthouse's business.

Now what

Credit Suisse's new price target also implies that even after today's steep sell-off, there could be a further 33% downside risk in Brighthouse stock. Considering that the stock wasn't particularly cheap to begin with -- selling for more than 20 times earnings -- it's understandable that investors are fleeing from it today.