Walter Swinburn is to quit as a trainer on 31 October - although he may return if a backer can be found.
The former jockey, 50, won the Epsom Derby three times as a rider, including the 1981 contest on Shergar.
He took over the training licence from his father-in-law, Peter Harris, in November 2004 and sent out over 260 winners from his yard in Hertfordshire.
But with Harris ending his 30-year link with racing, Swinburn told the Racing Post: "A big decision had to be made"
He added: "With a big yard like this you need the boxes full up, and Peter is the main owner. To suddenly find you are minus 50 horses would not have been a good starting point.
"I'm very confident you haven't seen the last of me as a trainer, but the advice from the accountants and so on was that it wasn't viable at the moment.
"When I'd listened to their advice I was happy to take it. I just need to take a step back and it feels the right decision."
Harris said: "I'm sure the economic climate has played its part and my decision would reduce his numbers of horses in training."
Swinburn landed one of the biggest victories of his training career earlier this season when Julienas won the Royal Hunt Cup at Ascot.