  National economies rest on networks of millions of customer-supplier
relations. Some companies -- in the case of their default -- can trigger
significant cascades of shock in the supply-chain network and are thus
systemically risky. Up to now, systemic risk of individual companies was
practically not quantifiable, due to the unavailability of firm-level
transaction data. So far, economic shocks are typically studied in the
framework of input-output analysis on the industry-level that can't relate risk
to individual firms. Exact firm-level supply networks based on tax or payment
data exist only for very few countries. Here we explore to what extent
telecommunication data can be used as an inexpensive, easily available, and
real-time alternative to reconstruct national supply networks on the
firm-level. We find that the conditional probability of correctly identifying a
true customer-supplier link -- given a communication link exists -- is about
90%. This quality level allows us to reliably estimate a systemic risk profile
of an entire country that serves as a proxy for the resilience of its economy.
In particular, we are able to identify the high systemic risk companies. We
find that 65 firms have the potential to trigger large cascades of disruption
in production chains that could cause severe damages in the economy. We verify
that the topological features of the inter-firm communication network are
highly similar to national production networks with exact firm-level
interactions.
