It's an accepted belief among tech startups that it's OK to grow fast at the sake of profits. But what if the company is 27 years old?

Under the new ownership of SoftBank Group Corp., the once relatively conservative U.K. chip company ARM Holdings PLC has rapidly expanded in size and head count, and returned a sizable loss.

ARM — founded in late 1990 — posted a loss of $200 million for the nine months to Dec. 31, off net sales of $1.4 billion, according to SoftBank's consolidated results published Wednesday.