Paris suburbs

I have visited one of university in Paris, excalty in Paris suburbs to attend a financial seminar.
One of their topic was about some estimation of correlations. A speaker who is a famous researcher talked in English very fulently, but it was difficult to understand it. The claim was that we can estimate the correlation among company's stocks by using asymptotic expansions even in condition that we only 'observe' them during some discrete-time. He called them 'observation time', and he formulated them by poisson-time.
I think it is very interesting because a correlation is important for finance. Of course we have many ways of its estimation, but implying or hedging the correlation may be impossible by using financial instruments. If this research is more advanced, it will be tradable.