Shares in Anworth Mortgage Asset Corp. dropped nearly 20 percent Thursday after concerns of meltdowns in the mortgage and credit markets made investors uneasy.

The drop came after the Santa Monica-based company said earlier this week that its Belvedere Trust Secured Assets Corp. unit recently received default notices from WaMu Capital Corp., Barclays Capital Inc. and Deutsche Bank Securities Inc. and would be forced to sell most of its assets in order to pay. Lenders have a right to call in loans when the collateral securing a loan loses its value. As of Aug. 8, the company owed about $140 million.

Investors have become leery about even safe mortgage investments due to declining confidence in the market fueled by the slide of Countrywide Financial Corp. and the recent bankruptcy or shuttering of several other lenders.

Shares in Anworth dropped 76 cents, or 19.5 percent, to $3.14 in afternoon trading Thursday on the New York Stock Exchange. Shares have lost 36 percent this week.