Tough times on Wall Street are reaching all the way to the highest levels of the most storied former investment bank—Goldman Sachs—as partners there are being forced to borrow money to cover margin calls, according to sources within the firm.

Several Goldman Sachs partners have leveraged their Goldman Sachs stock to buy alternative investments such as hedge funds & private equity, and they have done so through their Goldman Sachs brokerage accounts.

But Goldman stock has declined in value by more than 50 percent since last spring, meaning that Goldman Sachs is in the awkward position of making margin calls on its own partners, who can't meet those calls because their alternative investments are underwater and they don't have enough cash on hand.