This is the result of the legislative shell game of the past seven years where the state budget was "reduced" by not fully funding pension obligations. Alaska's pensions are currently only 60% funded so that can has been kicked down the road for some time. This shell game will collapse in the next couple of years and it won't be good for the state or its future.  Nat pointed out as did Tom and Robin's links that the 6 year rate of return is less than 6.7% with a 1 year return of -0.36%.  Remember the 9.3% growth over the last 7 years is due to the market crash in 2009. The stock market is probably as high as it is going to go short term and likely in for a correction soon (December Fed meeting). What happens if there is a 10% downward correction? World markets are not in a healthy state and relying on a "gamble" in the bond market is not prudent. 
I'm sure a New York bond issuer will gladly set up Alaska bonds as they makes money regardless of performance. It's a con game.