Bloomberg reported yesterday that Coinbase is offering accredited investors the opportunity to purchase an index fund; a basket of four cryptocurrencies listed on their exchange:
Bitcoin
Ethereum
Litecoin
Bitcoin Cash
At the same time, Coinbase launched 'Coinbase Index', described as "a measure of the financial performance of all assets listed on GDAX, weighted by their market capitalization."
It can be viewed here:
With details on how it's constructed here: