Please explain....http://finance.yahoo.com/q?s=GBTC

Closed today at $100. Why?   (that is $1000 per btc, right?)

Yes,

http://www.otcmarkets.com/stock/GBTC/quote
site says.....Common Stock - Each GBTC share represents ownership of approximately 0.1 bitcoin

Why is BTC at $1000 OTC, but you can actually BUY them from Coinbase for ~585?

Former Bitcoin King is Bankrupt and could be rich again.

https://www.wsj.com/articles/former-bitcoin-king-is-bankruptand-he-could-get-rich-again-1510223405

because the claims by people who deposited bitcoin at Mt. Gox are calculated based on the yen value of the cryptocurrency at the beginning of Mt. Gox liquidation proceedings in April 2014
...
Mr. Karpelès’s company, called Tibanne, owns about 88% of Mt. Gox.

The bankruptcy estate for Mt. Gox holds 202,185 bitcoins worth about ¥169 billion or $1.5 billion at current rates. Meanwhile, the trustee has recognized claims by exchange customers of ¥46 billion based on the April 2014 bitcoin price, a procedure that lawyers say has a sound basis in bankruptcy law.
...

Omg...Karpelès.....Bankrupty laws make no sense.  How can they make him a billionaire???   Really!!!!!

Fed’s Dudley Warns on Dangerous ‘Speculative Mania’ Around Cryptocurrencies

https://www.wsj.com/articles/feds-dudley-says-puerto-rico-has-difficult-recovery-process-ahead-of-it-1519311605