Resist composition, method of forming resist pattern, novel compound, and acid generator

A resist composition comprising a base component (A) which exhibits changed solubility in an alkali developing solution under action of acid and an acid-generator component (B) which generates acid upon exposure,

• said component (B) comprising an acid generator (B1′) comprised of a compound represented by formula (b1-1′) shown below:
• wherein each of R1″ to R3″ independently represents an aryl group which may have a substituent or an alkyl group which may have a substituent, with the provision that at least one of R1″ to R3″ represents a substituted aryl group having part of the hydrogen atoms substituted with a group represented by formula (b1-1-0) shown below, and two of R1″ to R3″ may be bonded to each other to form a ring with the sulfur atom;
• X10 represents an unsubstituted aliphatic polycyclic group;
• Q3 represents a single bond, or an alkylene group, a fluorinated alkylene group, —O—, —C(═O)—O—, —C(═O)—NH—, —C(═O)—, —O—C(═O)—O—, or a combination of the aforementioned groups;
• Y represents —C(═O)— or —SO2—;
• and Y11 represents an alkyl group of 1 to 10 carbon atoms which may have a substituent or a fluorinated alkyl group which may have a substituent:
• wherein W represents a linear or branched alkylene group of 2 to 10 carbon atoms.