Question 1 June 2008 past papers exam

Hi Mike,

I was practicing with past papers exam and I was doing question one from June 2008. In the big question there is a note about bonus that has to be paid to employees: half cash and half share options. I will quote the note below:
“(v) The directors of Ribby announced on 1 June 2007 that a bonus of $6 million would be paid to the employeesof Ribby if they achieved a certain target production level by 31 May 2008. The bonus is to be paid partly in
cash and partly in share options. Half of the bonus will be paid in cash on 30 November 2008 whether or not the employees are still working for Ribby. The other half will be given in share options on the same date, provided
that the employee is still in service on 30 November 2008. The exercise price and number of options will be fixed by management on 30 November 2008. The target production was met and management expect 10% of employees to leave between 31 May 2008 and 30 November 2008. No entry has been made in the financial statements of Ribby.”
I tried to do by myself this note before going with the consolidation issues that were tested in this question and I checked this part in the asnwers. Below is the answer from ACCA website:
Bonus to employees of Ribby
A liability of $3 million should be accrued for the bonus to be paid in cash to the employees of Ribby. The management should also recognise an expense of (2/3 x 90% x $3 million) $1.8 million, with a corresponding increase in equity. The
terms of the share options have not been fixed and, therefore, the grant date becomes 30 November 2008 as this is
the date that the terms and conditions will be fixed. However, IFRS2 requires the entity to recognise the services when
received and, therefore, adjustment is required to the financial statements. Once the terms are fixed, the fair value can
be calculated and any adjustments made.
$m
DR Expense – in retained earnings 4·8
CR Equity 1·8
CR Current liabilities 3
I cannot understand why they used 2/3 for the share options amount because it is not specified any vesting period. Everything else is prety straightforward to me.
Could you please kindly help me to understand this?

Thank you so much Mike.
Ionela