Foundation trust regulator Monitor is anticipating that some 47 acute and mental health trusts will not make it to foundation trust status by 2010.
The forecast is contained in Monitor's business plan for 2008-09, which shows how many assessments the regulator expects to do over the next two years. By April 2009 it expects to have completed 64 more assessments, with 45 trusts passing. The following year it expects a further 56 trusts to gain foundation status, bringing the total to 193 out of a possible 240.
The Department of Health has already said that the options for trusts failing to reach foundation status are merger or takeover by an existing foundation.
A spokesman for Monitor said the projections were based on the number of applications the regulator was able to consider a year and the pass rate of two out of three.
He said: "Monitor has agreed with the Department of Health to expand our assessment capacity in order to assess more applications for NHS foundation trust status. But it should be clear that an increase in capacity does not represent a lowering of the bar on quality."