  In an era of rapid technological advancements and macroeconomic shifts,
worker reallocation is necessary, yet responses to labor market shocks remain
sluggish, making it crucial to identify bottlenecks in occupational transitions
to understand labor market dynamics and improve mobility. In this study, we
analyze French occupational data to uncover patterns of worker mobility and
pinpoint specific occupations that act as bottlenecks which impede rapid
reallocation. We introduce two metrics, transferability and accessibility, to
quantify the diversity of occupational transitions and find that bottlenecks
can be explained by a condensation effect of occupations with high
accessibility but low transferability. Transferability measures the variety of
transitions from an occupation to others, while accessibility assesses the
variety of transitions into an occupation. We provide a comprehensive framework
for analyzing occupational complexity and mobility patterns, offering insights
into potential barriers and pathways for efficient retraining programs. We
argue that our approach can inform policymakers and stakeholders aiming to
enhance labor market efficiency and support workforce adaptability.
