LONDON (CNNMoney.com) -- Dealmakers, investors and home owners in the United States are facing a grim summer as conditions for borrowers get worse.

Until recently, there has been a seemingly unlimited supply of cheap money to fuel leveraged buyouts and other takeovers. There was also an easy flow of mortgage money available before the housing market turned south and the crisis erupted in subprime mortgages made to borrowers with poor credit.

But now investors are showing a greater disdain for risky debt - and fears about a looming credit crunch have shaken investor confidence worldwide. The Dow Jones industrial average plunged 311 points Thursday - its second-worst day of the year - and sent global stock markets reeling. The Dow opened lower Friday as well but later stabilized and was little changed in mid-morning.

Besides triggering a global stock selloff, the jitters are casting a shadow on the buyout boom and could slow down everything from private equity deals to corporate restructuring plans.