Is hacker news rigged?

4 see 4 items for "yardsale" on main "http://news.ycombinator.com/" page today 6/21? how can that happen?

why so much karma to yard sale news?

here:

http://news.ycombinator.com/item?id=4142649

http://news.ycombinator.com/item?id=4142376

http://news.ycombinator.com/item?id=4142338

http://news.ycombinator.com/item?id=4142768

this seriously undermines hacker news!