Looking at historical results for holding a $10,000 investment in VSMGX over periods of two years:

VSMGX: Vanguard LifeStrategy Moderate Growth

11/1994 - 6/2019; 296 months total

(limited by range of available data for VSMGX):

Length of holding period: 24 months

Total number of overlapping 24-month periods: 273

Average number of dollars earned in 24 months on a $10,000 investment: $1622.31

Average CAGR (annualized rate of return) of those 273 24-month periods: 7.81%

Standard deviation (σ) of single-month returns, annualized): 9.49%

Frequency of underperformance:

Number of periods in which VSMGX made less than VMMXX: 60/273 = 22.0%

Number of periods in which VSMGX lost money: 47/273 = 17.2%

Number of periods in which VSMGX failed to keep up with inflation: 55/273 = 20.1%

Average amount of underperformance in the times where it occurred:

Versus VMMXX over those 60 loss periods: -$1537.97

Dollar loss: -$1212.02

Real loss of purchasing power (inflation-adjusted): -$1401.48

Worst single 24-month performance:

Compared to VMMXX, 3/2007 - 2/2009: -$3921.53

Dollar loss, 3/2007 - 2/2009: -$3176.54

Real loss of purchasing power (inflation-adjusted), 3/2007 - 2/2009: -$3603.77

Reward for taking that risk:

Additional return above VMMXX, averaged over 24-month periods: +$1123.09

Return in dollars: +$1622.31

Real return above inflation: +$1180.26

Link to Morningstar chart for that worst period:

VSMGX vs VMMXX, 3/2007 - 2/2009
Annual income twenty pounds, annual expenditure nineteen nineteen and six, result happiness; Annual income twenty pounds, annual expenditure twenty pounds ought and six, result misery.