SNDK: $900 In Play After Failed Test of H&S Neckline and 50 MASandisk CorporationBATS:SNDKtimothysmith78Sandisk (SNDK) shares tumbled 6% in premarket trading on Tuesday, adding to Friday's 11% drop as concerns intensified about increasing competition in global memory and AI related chip markets following the successful Shanghai IPO launch of Chinese memory maker CXMT. The stock has soared more than 400% since the start of the year amid a memory chip shortage fueled by AI infrastructure demand. Taking a closer look at the technicals, the stock recently broke down below the neckline of a head and shoulders (H&S) pattern, a chart formation that indicates a potential top and downward trend reversal. After the breakdown, the price staged a short-lived countertrend move to test the pattern's neckline and 50 MA but encountered heavy selling and has continued lower. If the shares continue their decline, traders should keep a close eye on key support around $99. Traders could seek entry points in this area just above the upward sloping 200 MA and a brief consolidation period in mid April during the stock's strong trend higher during the second quarter.