Vohratom C:C is undefined, nest with bycol and its range define in LAMBDA,it will work.
{"DIVIDEND"; BYROW(A2:A; LAMBDA(r;BYCOL(C2:C;LAMBDA (c,IF(c="Dividend";IFNA(SUBSTITUTE(IMPORTXML(CONCATENATE("https://finviz.com/quote.ashx?t=";r);'XML IMPORT'!C$3)));".";",")/4);"-")))}
Check 2 close parenthesis ,if I was misplaced