Telegram raised $850 million from 94 investors in March in addition to $850 million it gained in February, and “may pursue one or more subsequent offerings,”.
This makes Telegram ICO the largest Initial Coin Offering in the World (yes, EOS not included).
“Raising the planned amount is a success for Telegram, given that the Bitcoin decline in recent weeks made investors more cautious toward crypto-assets,"
Telegram plans to use the capital from the ICO to develop it's own blockchain, a "Telegram Open Network" with "Gram" cryptocurrency.
Telegram however got into some trouble in Russia after refusing to hand over users' encryption keys to the authorities. It's possible Telegram will be blocked in Russia as a result of this.
It was easy for Telgram to achieve this milestone because it is already very popular and trustworthy. I'm in support of them not giving their keys tho.
If they gave the keys away to Russians they'd be done for good. This business is founded on trust and trust is something which takes a lot of effort and time to build up and it's very easy to lose.