when global markets get shaky investors might shift their investments from one market to another in an effort to insulate from spillover effects such a shift may lead to positive boosts in those safe haven markets 
this effect was seen with the u s investment inflows during the eu s struggles with the greek debt crisis in 2015 when dollars flow into u s treasuries the yield goes down along with the borrowing cost for american homebuyers borrowers and businesses this is an example of a positive spillover effect from the perspective of a u s consumer 