Catch up on today's top five analyst downgrades with this list compiled by The Fly: 1. Barnes & Noble (BKS) downgraded to Hold from Buy at Gabelli with analyst John Tinker citing the termination of Chief Executive Officer Ron Boire and saying the firing was a surprise as Mr. Boire hosted the recent investor meeting at which a new store strategy was officially announced. 2. 21Vianet (VNET) downgraded to Underweight from Neutral at JPMorgan with analyst Michelle Wei citing the company's second quarter results. 3. Cree (CREE) downgraded to Sell from Neutral at UBS and to Market Perform from Outperform at Northland. 4. Mosaic (MOS) downgraded to Neutral from Positive at Susquehanna with analyst Don Carson saying his downgrade reflects a lower pricing outlook for potash, phosphate, and the likelihood for a limited recovery if any were to occur. Carson lowered his price target to $28 from $30 on Mosaic shares. 5. Dick's Sporting (DKS) downgraded to Neutral from Conviction Buy at Goldman with analyst Stephen Tanal saying he believes the stock's valuation has caught up with his earnings forecasts and sees "more limited" upside from current share levels. This list is just a portion of The Fly's full analyst coverage. To see The Fly's full Street Research coverage, click here.