Not in itself. If your arm impedes the ballhandler, it may be holding. If you hit them with your arm, that is also a foul. But "reaching in" is not the name of a foul.
This is covered on a list of 7 Basketball rule myths on NBA.com. (http://www.nba.com/jrnba/officials/officials_guide_section15.html)
1 rule is you can not run with the ball
There is no 90 second rule in basketball.
because that is the rule...
Because that is the rule.
The main rule in basketball is teamwork. It is in no way an individual sport.
Dunking is not allowed.
5 fouls out the game
There are many like the shotclock violation, 8second rule
if you travel in basketball, than it automaticly becomes the other teams ball.