This article investigates how Russian aspectual pairs from borrowed and colloquial verbs are formed. This question is relevant since the most common source languages of Russian loan verbs do not express the aspectual distinction [imperfective–perfective] morphologically. Seventeen new verbs, most of which belong to the technological sphere, were investigated in an online experiment (N=120), in which native Russian speakers were asked to form perfective counterparts for a number of new verbs, such as гуглить ‘to google’ and эсэмэсить ‘to text, to SMS’. The results show that there is variation in the formation of new verbs, but also that one form was chosen by most participants who formed a valid perfective. The most common perfectivizers in this experiment were the suffix -ну-, followed by the prefixes за-, про-, от- and с-. The suffix -ну- is especially productive in verbs denoting actions that can be carried out or finished in a short time, but is also found in verbs denoting longer processes. This use of -ну- is characteristic for verbs in Russian slang.