Financial failures, financial reconstruction, financial rescues - of banks above all - is a specialty of Macquarie Bank.Or it may well be, as the carnival of banking, self-harm the main act, unfolds into M&A in Australia. The tempo on this is picking up, the life and adviser divestment cycle only a taster of what's ahead from the test studio.Dramas aplenty face Macquarie Bank, its own banking business near the highest-risk of any in the Australian industry.Macquarie's banking enterprise, framed on the legacy of Hill Samuel, is a growth story and a decisive one if based on the March 2018 full year results for the bank and Macquarie Group.The jump in the profit of the banking and financial services business of the bank - BFS - is mischief that group CEO Nicholas Moore admires."It's very important … to see the result step up. It's a positive number," Moore told a briefing on Friday morning.BFS delivered a net profit contribution of A$560 million for the group's 2018 financial year, up nine per cent from $513 million in 2017, the bank's annual report shows. A one-off gain from selling the life business out of the bank last year makes this year's profit surge all the more profound.The Macquarie Bank banking business will look sturdy to some eyes, $40 billion in mortgages and business lending supported by $45.7 billion in deposits.Mortgages funded by Macquarie are 1.95 per cent of the $1.6 trillion funded by Australia's banks so far. Peanuts. The bank's market share is still but one-tenth of that commanded by NAB, the also ran in mortgage land.At $31.3 billion (APRA's number) the bank has multiplied its home loan book by 3.3 times since December 2002, the beginning of the regulator's monthly dataset. The whole of the country's mortgage market multiplied 2.4 times over that period.Over the past five years alone the system growth multiple for Macquarie is a pretty incredible 5.0 times.Only ANZ, of the big banks, has a system growth multiple over the same period, being 1.2 times.Over just the last year the Macquarie system multiple was around 2.4 times so, when the slump hits, the bank and Macquarie Group will be hit hard.One buffer for the bank is a marked story of decline projected in the cost to income ratio.This is now less than 50 per cent and being steered toward less than 40 per cent, Greg Ward, the bank's managing director told the briefing.Banking and Financial Services is one of "three significant businesses which are delivering superior returns following years of investment and acquisitions," Moore said.BFS, along with Corporate and Asset Finance and Macquarie Asset Management producing a combined 23 per cent return on equity. This compares with a return of 15 per cent for the capital markets facing businesses of the bunk, a distinction drawn by the group.Top returns for the bank - pushing twice those of big banks - are one of the forces behind $4.2 billion in "surplus capital".