* Q4 EPS 9 cents miss estimates by 6 cents

* Q4 rev misses Street expectations

* Saw greater pricing pressure from customers, competitors

* Says not to provide outlook for Q1

* Shares fall 18 percent in after-hours trade (Adds conference call details)

By Shrutika Verma

BANGALORE, May 13 (Reuters) - CommVault Systems Inc (CVLT.O: Quote, Profile, Research), posted lower-than-expected quarterly earnings and said it would not give a first-quarter outlook due to economic uncertainities, sending its shares tumbling as much as 18 percent in after-hours trade.

The data management software provider has been hit by the weak economy as customers tend to pull back on data backup services that CommVault offers.

"The negative impact from the recession affected our business in a number of ways...customers froze budgets, customers reduced their budgets," Chief Executive Robert Hammer said on a conference call with analysts.