SoftBank CEO Masayoshi Son won't call WeWork a rescue, saying instead that the latest financing allowed his company to dramatically reduce the average share price it paid for the coworking company. Nevertheless, he described it as an "exception" that won't happen again.

SoftBank will make "no investment for the purpose of rescue," Son told investors on Wednesday, after the Japanese conglomerate reported its first quarterly loss in 14 years. He said portfolio companies must be "self-financing," and "that's something that I would like to clearly extend my message to you."

Son acknowledged making some mistakes in his investment strategy and accepted that WeWork's dramatic fall in recent months has led some to question his judgment and the viability of SoftBank's massive Vision Fund. SoftBank recorded a 374.7 billion yen ($3.4 billion) writedown on its WeWork investment about two weeks after taking 80% control of the company with a new $5 billion financing package.

WeWork was forced to pull its IPO at the end of September because of mounting losses and an unwillingness of public investors to fund the business. SoftBank ousted former CEO Adam Neumann, who walked away with more than $1 billion, and installed Marcelo Claure, SoftBank's operating chief, as executive chairman. Son said there will be no future bailouts for SoftBank-backed start-ups.