Lehman’s heavy subprime exposure and thus-far minimal writedowns are making investors jittery, reports BusinessWeek.

Shares in the Wall Street bank Lehman nearly half their value yesterday on the coattails of the Bear Stearns meltdown, before finishing down 19%.

Lehman’s fiscal first-quarter earnings, announced today, fell 57% due to a steep decline in its capital markets business, but its shares soared as it easily beat Wall Street forecasts.

“The government bailout of Bear Stearns puts the increasing vulnerability of banks front and center,” says Andrew Gordon.

“They have a long way to go before they get a clean bill of health. Heck, they have a long way to go before they hit bottom and start turning things around.

“We can’t wait that long. Even in their weakened state, we need banks to do what they do – lend. Somebody – Ben, are you listening? – needs to administer a shot of adrenalin to these moribund financial institutions. And the sooner the better.”