Jakarta, June 5 -- Indonesia's financial regulator sought to reassure investors after the Jakarta Composite Index capped a turbulent week with a 4.20 percent decline to 5,594.77, saying corporate earnings and market fundamentals remain resilient despite mounting volatility.

The Financial Services Authority, or OJK, said listed companies posted aggregate first-quarter profit growth of more than 21 percent from a year earlier, underscoring the strength of corporate performance.

"Most listed companies continued to generate profits," Hasan Fawzi, OJK's chief executive for capital market supervision, said at a press briefing on Friday.

Historical performance data and earnings prospects should provide investors with a rational basis for eval...