I thought about the problem a bit more and given we can assume it is a time range if I knew where the maximum number was in the array i could get that index and work backward. Once I thought of the problem that way and with the key statement you gave me to watch out for those ranges that could go up and down. A sample result would look like this…

stock.rb

#!/usr/bin/env ruby -wKU
require "test/unit"

class Stock
  # To change this template use File | Settings | File Templates.
  def self.find_longest_run(prices=[])
    return {:low=>{0.0=>0},:high=>{0.0=>0}} if prices.nil? || prices.size == 0
    result = {}
    # start at the end
    #find the highest value
    index_and_max_value = prices.each_with_index.max
    result[:high] = Hash[*index_and_max_value.flatten]

    #p result[:high]
    #remove any values after the highest value
    left_prices = prices[0..result[:high].values.first]
    index_and_min_value = left_prices.each_with_index.min
    result[:low] = Hash[*index_and_min_value.flatten]

    result
  end
end

class TestStock < Test::Unit::TestCase
  def test__standard_range
    puts "testing standard range"

    prices = %w{2 1 2 3 2}.collect!{|i| i.to_f}
    result = Stock.find_longest_run(prices)
    puts "Result: #{result}"
    assert result[:low].values.first.eql?(1)
    assert result[:high].values.first.eql?(3)
  end
  def test__inner_range
    puts "testing inner range"

    prices = %w{10 5 10 15 20 12 30 2}.collect!{|i| i.to_f}
    result = Stock.find_longest_run(prices)
    puts "Result: #{result}"
    assert result[:low].values.first.eql?(1)
    assert result[:high].values.first.eql?(6)
  end
  def test__no_values
    puts "testing no values"

    result = Stock.find_longest_run(nil)
    puts "Result: #{result}"
    assert result[:low].values.first.eql?(0)
    assert result[:high].values.first.eql?(0)
  end

  def test__msft
    puts "testing msft"
    prices = [17.47, 24.6, 23.77, 22.03, 27.29, 27.87, 29.41, 26.66, 22.98, 20.61, 23.42, 25.86, 26.69, 25.66, 23.5, 24.29, 21.05, 20.51, 22.03, 19.33, 19.77, 17.62, 21.54, 23.23, 20.83, 19.12, 19.15, 19.57, 20.67, 19.89, 20.72, 21.34, 21.43, 22.47, 21.25, 20.9, 22.24, 22.47, 21.56, 20.26, 21.24, 21.32, 23.21, 23.16, 22.25, 22.54, 22.8, 24.36, 24.28, 23.88, 22.93, 22.03, 23.06, 23.59, 22.71, 23.41, 25.11, 23.59, 23.56, 25.45, 24.05, 25.89, 24.79, 25.11, 22.28, 20.98, 21.58, 22.29, 23.89, 25.43, 26.69, 27.39, 27.86, 28.79, 26.37, 26.09, 28.03, 28.82, 27.68, 27.23, 27.08, 27.77, 34.69, 31.77, 33.66, 30.83, 25.82, 26.94, 27.07, 26.98, 26.21, 24.5, 26.1, 25.53, 21.36, 19.47, 18.72, 16.47, 15.66, 17.81, 19.64, 20.38, 23.19, 22.95, 24.19, 25.24, 27.21, 28.99, 30.04, 27.77, 28.39, 29.0, 30.24, 25.66, 22.89, 25.67, 23.47, 24.49, 26.67, 26.95].collect!{|i| i.to_f}
    result = Stock.find_longest_run(prices)
    puts "Result: #{result}"
    assert result[:low].values.first.eql?(0)
    assert result[:high].values.first.eql?(82)
  end
end

test output

/Users/tom/.rbenv/versions/1.9.3-p194/bin/ruby -e $stdout.sync=true;$stderr.sync=true;load($0=ARGV.shift) /Users/tom/Workspace/linked_list/stock.rb
Run options: 

# Running tests:

testing inner range
Result: {:high=>{30.0=>6}, :low=>{5.0=>1}}
.testing msft
Result: {:high=>{34.69=>82}, :low=>{17.47=>0}}
.testing no values
Result: {:low=>{0.0=>0}, :high=>{0.0=>0}}
.testing standard range
Result: {:high=>{3.0=>3}, :low=>{1.0=>1}}
.

Finished tests in 0.001186s, 3372.6813 tests/s, 6745.3626 assertions/s.

4 tests, 8 assertions, 0 failures, 0 errors, 0 skips

Process finished with exit code 0