The net profit of Bulgarian state-owned Electricity System Operator (ESO) decreased to 25.1 million levs in the first nine months of 2018 from 43.4 million levs in the same period of last year, following a decline in revenue, the company's financial statement showed. The company's total operating revenue fell to 456.1 million levs in the January-September period of 2018, compared to 508.3 million levs in the corresponding period of last year, according to figures from ESO's interim financial statement.ESO's sales revenue decreased to 423.8 million levs in the review period from 453.2 million levs a year earlier, while other operating dropped to 32.3 million levs from 55.1 million levs the year before. The power system operator's expenses for electricity on the balancing market fell significantly to 70.1 million levs in the period under review from 126.0 million levs in the same period of 2017, while its technological electricity transmission costs rose to 76.6 million levs from 62.3 million levs.