(Bloomberg) Peruvian presidential front-runner Pedro Castillo, whose leftist policies have rattled investors, saw his once-wide lead narrow to within the margin of error in a new poll.A survey by Datum Internacional published Friday gave Castillo, with the Free Peru party, 42% of voter intention versus Keiko Fujimori, with the Popular Force party, at 40%.Datum said 11% of respondents plan to cast blank ballots a form of protest and 7% remain undecided ahead of the June 6 runoff.The poll matches other surveys that show Castillo’s once double-digit lead dwindling fast. In April, Datum gave Castillo a 15 percentage-point advantage over Fujimori and last week he was still five percentage points ahead.Peruvian bond and currency markets have been whipsawed in recent weeks by Castillo’s sudden rise and prolonged fall in the polls. The nation’s stocks and bonds rallied on Friday, with its 2051 dollar bond on track for its biggest jump in a week, while the benchmark s