In a paper cited almost 5000 times, published in 2001 in Review of General Psychology, Roy F Baumeister, Ellen Bratslavsky, Catrin Finkenauer and Kathleen D Vohs showed that bad actually seems to be stronger than good.
Bad events, bad emotions, bad feedback and bad parents have in numerous studies been shown more influential compared to similar but good "inputs". Not very surprising lots of studies have show humans in general are more motivated to try to avoid bad outcomes than to the strive for good outcomes.
This tendency to react stronger on bad outcomes is most probably the reason why media, in general, gives much more space to bad, rather than good news.
Reference
Baumeister, R. F., Bratslavsky, E., Finkenauer, C., & Vohs, K. D. (2001). Bad is stronger than good. Review of general psychology, 5(4), 323.
