By Maxx Chatsko This small-cap biotech highlights the central rule of biotech investing. The S&P 500 may have only recently entered a bear market, but the biotech sector has been reeling in one for most of 2022. Although many biotech stocks have tumbled 50% or more since the beginning of the year, most of the pain was deserved. Momentum pushed too many companies in the sector to unsustainable and unrealistic valuations last year – and the bill always comes due. Despite the carnage, investors should be comforted knowing de-risking events still dictate valuations in time frames that matter. If y…