Uber raised a total of more than $2 billion from investors in June and December last year — and is now back for another round. The anonymous messaging start-up Yik Yak collected $73.5 million in three financing rounds in seven months, and Zenefits, a human resources start-up, raised more than $580 million in less than two years, with the latest deal done last week.

The pace of technological change has long been happening at the lightning-fast speed of the Internet. Now, start-up financing is increasingly taking place at that speed as well.

Uber is just one example of the quickening tempo. The ride-hailing company is in discussions to raise around $1.5 billion in financing, which could value it at $50 billion. Just five months ago the company collected $1.2 billion for its war chest, an amount that later swelled with the addition of a strategic investor.

And the rate of fund-raising by Uber — and across the start-up landscape — has little precedent, driven by money pouring in from hedge funds, strategic investors and more, and by the willingness of entrepreneurs to embrace the cash.