Prefixal productivity is attested in all Indo-European languages and is reconstructed in the proto-languages of all major Indo-European languages families. It is particularly important for under-standing the origin of many non-primary verbal roots in all these languages. Surprisingly, only a handful of etymons involving prefixation have been reconstructed at the PIE level. A systematic study of this word formation process in PIE remains to be carried out. It could result in a better understanding of the origin of a number of PIE roots, especially complex roots with limited attestation, and help explain attested words in daughter languages that need a convincing etymology. In our talk, we will show how a better understanding of the role of prefixes in (secondary) verbal root formation can result in new etymological insights. Such analyses have already been proposed for several examples. For instance, with the compensatory lenghtening *Ce=HC- > *CV̄C-, Weiss (1993) analyses Lat. pālārī ‘to wander’ as reflecting *pe=h2lh2-ó- > *pālH-āye/o-. Another classical example of the same prefix is Arm. p‘law < *p‘ulaw < *pōlH-to based on *pe=h3lh1-, as also P.- Germ. *fall-an- ‘to fall’ < *pŏlle/o- (with Osthoff’s shorthening) < *pōlle/o- < *pōlH-é/ó- (Praust 2005; Neri 2007; Kroonen 2013: 125–6; Dunkel 2014 II: 82). Other examples include PIE *pro=h1ed- ‘to devour’ > P.-Germ. *fr(a)-et-an-, (Scheungraber 2016: §4), PIE *kom=pro=h1ṇḱ- ‘to bring’ > P.-Germ. *breng-an- (Kroonen 2013: 77), PIE *°kom=h1ep- ‘to give’ > P.-Germ. *geb-an- (Kortlandt 1992) and *pe=h2ṛk- > Lat. parcō (Weiss 1993; cf. Hitt. pē=ḫark- ‘to hold off’). We intend to show that this word formation process is by far more widespread than usually thought. We shall discuss several examples, thus unifying sets of semantically similar roots and proposing novel etymologies for several difficult words. These views may shed some light on the possibility that PIE may have been (once) a satellite-framed language.