The study analyses the debate around the ambiguous relationship between firm size and performance. We explore how productivity varies across firm sizes in the informal sector, where firm size is sensitive to formal regulations. Additionally, the study also looks into the informal firms’ quantity and quality of employment by observing wage and performance dispersion across firm sizes, thus indicating capital accumulation and exploitation. Considering the data limitations, a pseudo-panel data design was adopted by combining the three, only available, independent cross-sectional surveys by the National Sample Survey Office, spanning from 1999–2000 to 2015–2016. Potential issues such as time-invariant unobserved firm-level heterogeneity were accounted for by using panel random effects regression. Using total firm employment and total factor productivity as the primary measures of firm size and performance, we find a positive relationship between the two across all major industries. Our results stand robust against alternative firm size and performance measures. However, this positive association between size and performance indicated capital accumulation (increasing productivity with increasing size) at the expense of labour exploitation (stagnant wages across firm sizes). The obtained findings convey important policy implications for adopting a carrot-and-stick approach for the gradual formalisation of the economy. JEL Codes: D22, L25, O25