As inventory in Boston and across the country expands, rents are dropping quickly in major metro areas. Sellers who don’t need to sell or can’t get the price they want list their homes on the rental market as well as the sales market. Boston ranked as 10th on Business Week’s list of metro areas with the largest rent drops in the Q4 2008 compared to Q4 2007. According to the study, Boston rents slid 2.8% year-over-year to an effective rent of $1,634.20 per month. With large job cuts in the financial industry hitting local employers like State Street and Fidelity Investments, the unemployment rate climbed to 5.0% in November 2008 compared to 3.6% in November 2007. The apartment vacancy rate hit 6.0% in the fourth quarter last year from 4.7% in the same period in 2007. Boston landlords are giving an average of 1.3 weeks of rent concessions.