Capital One Financial Corp., the big Falls Church credit-card company, last week let investment analysts in on new details of its famously successful and secret marketing operations and was rewarded with a $10 jump in its stock price.

Analysts who attended the company's annual investors conference said they came away believing that Capital One will be able to continue the growth that had produced a third-quarter profit increase of 30 percent.

Capital One and other financial stocks also were helped by perceptions that interest rates are not likely to rise much more, removing a potential threat to higher earnings.

With reports showing that inflation was low, thus reducing the likelihood of an increase in interest rates, stocks continued on a two-week run-up. The Washington Post-Bloomberg regional stock index gained 3.2 percent and is up nearly 5 percent over the past two weeks.

Shares of Tessco Technologies Inc. took their biggest leap in at least a year last week after the Hunt Valley, Md., company won a contract to serve as the spare-parts supplier for Nokia OY wireless telephones.

Tessco has handled Nokia's consumer hot line for four years and now will distribute more than 2,000 parts to 500 authorized service centers nationwide.

The week's biggest losses were suffered by stockholders of Bethesda-based Lockheed Martin Corp., shares of which fell $3.75 to $20, knocking more than $1.5 billion off the market value of the region's biggest defense contractor.

With Lockheed stock off from a high of $56.06 1/2 on Nov. 2, 1998, President Peter B. Teets took the fall and announced his retirement Friday.

The week's other conspicuous loser was Baltimore-based Sylvan Learning Systems Inc., which produced the quarterly earnings analysts had been expecting, but warned that growth will slow next year. Analysts quickly cut their earnings estimates and Sylvan stock lost more than $2.50 a share.