No.. the parentheses are not balanced.
|Group 1||Group 2||Group 3||Group 4|
Capture groups may be nested. A group consists of a left parenthesis and whatever is included up to its matching right parenthesis. This means that the characters that are captured by one group may also belong to another group.
Group numbering works as before:
Examine the following:
(((rat )bat )cat )(dog)
What subexpression does group 4 consist of?