I read a article in which it was mention that the bond of some company has outperformed the Bloomberg US high yield bond index by 2990 bps since 2016? and I am actually not able to understand What does it mean? Can somebody please explain me.

Many Thanks.

If the return on the index were, say, 10%, then the return on these bonds was 39.9%.

So does it mean spreads are or got tighter for this company?