Is it possible to profit from negative yield bonds?

Yes.

1. Purchase a negative yield bond (very foolish...)
2. Wait for interest rates to decrease (according to "the greater fool theory", there is always a greater fool...)
   • Here it should be stated that a negative interest rate decreasing will mean it becomes even more negative, meaning the price of the negative rate bond you're holding will increase so that it will too have the more negative rate as its effective rate
3. Watch the market price of your bond increase and sell it!

However, would I advise doing this? No. In today's interest rate environment, the best bets are stocks and short bonds or bank accounts for cash.

If someone buys a fixed rate treasury bond yielding -1% and checking account rates dropped to -2%, the buyer would benefit by avoiding even greater losses at the checking account rate.