The worth of hot technology start-ups seemed for years to go in only one direction: Straight up.
Now there are signs of growing unease over the dizzying valuations of some of the most richly priced private companies.
The latest sign has emerged with one such favorite, Snapchat, being discounted 25 per cent by one of its more recent investors, Fidelity, the mutual fund giant.
Another start-up, Dropbox, the widely used file storage service, was devalued by the giant asset manager BlackRock this year.
The funds' markdowns may.....