Complex sentence: The Merritt Brothers put their company stock up as collateral to borrow money from Rockefeller to fully fund the railroad, and in the span of only several months, the Merritt Brothers had lost their personal wealth and interest in both their mining and their railroad corporations.
Split into simpler sentences: The Merritt Brothers put their company stock up as collateral to borrow money from Rockefeller to fund the railroad. In the span of several months, the Merritt Brothers lost their personal wealth and interest in both their mining and railroad corporations.